LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

OIKT  OK 


-Received 
Accession  No. 


Class  No. 


I.  PROTOPHYTES 


THAL  LOGENS  m.  ACROGENS 


W.  ENDOGENS 


EXOGENS 


I.  PROTOZOA 


H.RADIATA 


IV.ARTICULATA 


m.MOLLUSCA 


WERTEBRATA 


BIOLOGICAL    TYPES. 


THE 


SCIENCE  OF  LIFE ; 


OR, 


ANIMAL  AND  VEGETABLE  BIOLOGY. 


BY 


REV.  J.  H.  WYTHE,  A.M.,  M.D., 

AUTHOR  OF  "AGREEMENT  OF  SCIENCE  AND  REVELATION,"  "THE  MICROSCOPIST,"  ETC 


NEW    YORK : 
PHILLIPS     &      HUNT 

CINCINNATI  : 
WALDEN     &     STOWE. 

l88o. 


'    COI'YRK'.IIT    I880,  BY 

ZEiTJUXTT, 
NEW  YORK. 


UNIVERSITY 


PREFACE. 


r  I  "HIS  book  is  written  for  those  who  have 
J-  some  elementary  knowledge  of  Physiology. 
It  gives  a  general  outline  of  the  origin,  structure, 
typical  forms,  and  functions  of  living  things,  so  as 
to  serve  as  an  introduction  to  the  examination  of 
the  objects  themselves. 

Although  a  text-book  must  of  necessity  be  a 
compilation  of  facts,  yet  many  years  of  practical 
experience  with  the  microscope  have  enabled  the 
writer  to  describe  many  things  with  the  confi- 
dence of  personal  observation.  Some  of  the  illus- 
trations are  original,  others  have  been  selected 
from  Dr.  Carpenter's  works  on  Physiology  and 
the  Microscope,  T.  R.  Jones  on  Zoology,  Lind- 
ley's  Botany,  Mac  Ginley's  Introduction  to  Biol- 
ogy, and  other  standard  works. 

It  has  been  the  aim  of  the  author  to  guide  the 

student   through   the   fundamental    principles  of 
1* 


6  PREFACE. 

Biology  to  the  contemplation  of  the  vast  temple 
of  animated  nature,  with  its  varied  compartments 
intimately  connected  with  each  other,  and  with 
the  central  one  of  all,  the  human  type.  In  every 
avenue  and  chamber  and  dome  of  this  wondrous 
edifice  the  Christian  student  recognizes  the  truth 

that  "  POWER  BELONGETH  UNTO  GOD." 
OAKLAND,  CAL.,   January,  1880. 


C  ONTENTS. 


.  HAPTlnt  PAGE 

I.  \VMAT  is  LIFE  ? 9 

II.  LIVING  MATTER 26 

III.  PARENTAGE 40 

IV.  TISSUE  FORMATION 52 

V.  TYPES  OF  CONSTRUCTION 72 

VI.  PROTOPHYTES 84 

VII.  THALLOGENS 98 

VIII.    ACROGENS 109 

IX.  ENDOGENS 122 

X.  EXOGENS 137 

XI.  PROTOZOA 161 

XII.  RADIATA 170 

XIII.  MOLLUSCA 192 

XIV.  ARTICULATA 213 

XV.  VERTEBRATA 239 

XVI.  THE  HUMAN  TYPE  . .  .281 


TJHI7BRSIT7 


THE 

SCIENCE    OF    LIFE. 

CHAPTER   I. 

WHAT    IS     LIFE? 

Am  I  but  what  I  seem — mere  flesh  and  blood  ? 
A  branching  channel,  and  a  mazy  flood  ? 
The  purple  stream  that  through  my  vessels  glides, 
Dull  and  unconscious  flows,  like  common  tides. 
The  pipes,  through  which  the  circling  juices  stray, 
Are  not  that  thinking  I,  no  more  than  they. 
This  frame,  comparted  with  transcendent  skill, 
Of  moving  joints,  obedient  to  my  will, 
Nursed  from  the  fruitful  glebe,  like  yonder  tree, 
Waxes  and  wastes  :  I  call  it  mine,  not  nit. 
New  matter  still  the  moldering  mass  sustains, 
The  mansion  changed,  the  tenant  still  remains ; 
And  from  the  fleeting  stream,  repaired  by  food, 
Distinct,  as  is  the  swimmer  from  the  flood. 

— ARBUTHNOT. 

i.  THE  term  Biology,  (from  the  Greek,  bios,  life,  and 
logos,  a  discourse,  or  doctrine,)  signifies  the  Science  of 
Life.  It  includes  the  study  of  all  the  phenomena  of  living 
beings,  both  animal  and  vegetable,  in  order  to  discover 
the  general  principles  which  underlie  their  origin,  for- 
mation, varieties,  and  functions.  The  special  study  of 
structure  is  termed  Morphology,  or  Anatomy.  The 
study  of  functions  is  Physiology.  The  origin,  develop- 
ment, and  arrangement  of  the  varieties  of  the  vegetable 
world  make  up  the  study  of  Botany.  Zoology  considers 


io  THE  SCIENCE  OF  LIFE. 

the  various  kinds  of  animals.  All  these  sciences,  and 
many  others,  combine  in  Biology. 

To  the  Christian  student  Biology  affords  a  multitude 
of  evidences  of  intelligent  design,  proving  the  universe 
to  be  the  product  of  Supreme  Will.  It  also  contains 
proof  of  the  reality  of  spiritual  existences,  in  addition 
to  physical  atoms  and  physical  forces. 

2.  The  cause  of  difference  between  the  living  and  the 
non-living  is  the  most  fundamental  question  of  Biology, 
and  the  answers  given  to  this  question  by  modern 
writers  depend  upon  the  schools  of  philosophy  to  which 
they  are  attached. 

Much  learning  and  industry  have  been  employed  within 
the  past  few  years  to  teach  the  system  of  Monism,  or  the 
theory  that  all  being  can  be  resolved  into  a  single  prin- 
ciple. Among  those  who  entertain  this  view,  some  hold 
to  materialism,  or  the  development  of  all  forms  from 
primitive  atoms.  Others  are  idealists,  conceiving  matter 
to  be  identical  with  force.  Others  again  are  pantheists, 
holding  that  mind  is  the  only  substance,  and  that  the 
universe  is  an  emanation  of  the  universal  mind. 

The  doctrine  of  rational  Dualism,  which  asserts  two 
real  principles  of  existence,  mind  and  matter,  with  their 
special  endowments  and  forces,  stands  in  opposition  to 
all  forms  of  Monism  whatever. 

Since  the  dawn  of  history  these  speculations  have  di- 
vided philosophers,  and  learning  of  all  kinds  has  been 
used  to  maintain  the  views  of  either  side.  Leucippus 
and  Democritus,  the  masters  of  Epicurus,  taught  the 
doctrine  of  invisible  and  indestructible  atoms,  with  spon- 
taneous motion,  as  the  cause  of  all  things.  Anaxagoras 


WHAT  is  LIFE? 

and  Plato  argued  for  a  regulating  intelligence,  producing 
order,  so  that  "  the  world's  activities  are  reflections  of 
God's  thoughts."  The  Hebrew  and  Christian  Script- 
ures, as  well  as  all  other  writings  which  exhibit  the 
religious  beliefs  of  mankind,  Koran  or  Shaster,  King  or 
Avesta,  (the  sacred  books  of  Mohammedans  and  Hindus, 
Chinese  and  Persians,)  teach  the  doctrine  of  Dualism,  or 
the  distinction  between  mind  and  matter. 

3.  The   revival  of    Monistic   philosophy  in    the    last 
century  has  awakened  much  discussion,  and  each  of  the 
sciences  in  turn  has  been  made  the  arena  of  conflict. 
In  Biology,  Darwin,  Spencer,  and  Haeckel  are  arrayed 
against  Agassiz,  Lionel  Beale,  and  M'Cosh,  and  the  con- 
test of  mind  has  brought  to  notice  a  wonderful  accumu- 
lation of  facts,  sufficient,  we  think,  to  settle  the  central 
question  of  philosophy  concerning  life. 

In  the  present  work  the  facts  of  Biology  are  regarded 
as  .confirmatory  of  the  principles  of  rational  Dualism.  In 
the  judgment  of  the  writer  there  is  no  conflict  between 
science  and  revealed  truth,  but  such  complete  agreement 
that  the  facts  of  science  can  be  best  understood  and 
explained  in  consistency  with  that  philosophy  which  re- 
ligion has  made  prevalent  in  the  minds  of  the  majority 
of  men.  Yet  the  learning  and  apparent  candor  of  many 
Monistic  writers  entitle  them  to  respect,  even  if  we  fail  to 
agree  with  them,  and  truth,  which  should  be  the  object 
of  all  study,  is  not  aided  by  epithets  or  personal  acri- 
mony. 

4.  Some  scientists  ignore  the  question  of  the  cause  of 
life,  and  confine  themselves  to  the  physical  and  chemical 
phenomena  associated  with  living  things;  but  this  is 


12  THE  SCIENCE  OF  LIFE. 

quite  unsatisfactory.  That  there  are  differences  between 
the  living  and  the  non-living  will  only  be  denied  by  the 
most  thorough  partisans  of  Monism.  These  differences 
depend  on  something  in  the  living  which  is  absent  from 
the  non-living.  In  common  parlance  we  call  it  life,  or 
life-force.  Such  a  life-force  is  as  necessary  to  Biology  as 
gravitation  is  to  Physics,  or  light  to  Optics. 

Writers  who  avoid  Dualism,  or  who  acknowledge 
antagonism  to  it,  have  not  been  able  to  give  a  clear 
definition  of  life. 

Bichat  defines  life  as  "  the  sum  of  the  functions  by 
which  death  is  resisted."  This  is  but  saying  that  life 
and  death  are  opposite  states. 

Dr.  W.  B.  Carpenter,  although  believing  in  the  difference 
between  mind  and  matter,  speaks  of  life  as  "  the  condi- 
tion of  a  being  which  exhibits  vital  actions ; "  which  is  but 
another  mode  of  stating  that  life  is  a  condition  or  state 
of  living. 

Coleridge  considered  life  as  synonymous  with  "  indi- 
viduation."  This  is  equivalent  to  separate  existence, 
and  includes  metals,  and  stones,  and  all  non-living  things. 

Herbert  Spencer  defines  life  as  "the  continuous  adjust- 
ment of  internal  relations  to  external  relations."  This 
definition  will  apply  to  a  boiling  tea-kettle,  a  steam- 
engine,  or  a  burning  candle,  as  well  as  to  a  living  thing. 

Haeckel  declares  "  that  all  natural  bodies  which  are 
known  to  us  are  equally  animated,  and  that  the  distinc- 
tion which  has  been  made  between  animate  and  inani- 
mate bodies  does  not  exist."  This  exceedingly  bold  and 
strange  statement  is  rendered  necessary  by  the  logical 
demands  of  the  Monistic  philosophy.  In  a  subsequent 


WHAT  is  LIFE?  13 

place  we  shall  examine  particularly  the  differences  be- 
tween animate  and  inanimate  bodies.  (See  Chap.  II.) 

All  such  definitions  and  statements  evade  the  real 
question :  that  is,  What  makes  the  difference  between  a 
living  body  and  the  same  body  a  moment  after  death  ? 

5.  The  cause  of  life  is  a  mystery  only  to  the  mate- 
rialist. To  the  Christian  philosopher  it  is  as  plainly 
revealed  as  any  other  fact  of  nature.  The  Bible  asserts 
that  life  results  from  the  union  of  a  spiritual  nature  with 
the  material  body.  In  other  words,  life  is  the  influence 
resulting  from  the  union  of  matter  and  spirit ;  and  this 
dualistic  theory  is  the  only  one  which  suffices  to  explain 
the  phenomena  of  living  things. 

Moses  declares  of  man  that  God  "  breathed  into  his 
nostrils  the  breath  of  life ;  and  man  became  a  living 
soul."  In  accordance  with  this  view  death  is  every- 
where referred  to  in  Scripture  as  a  departure  of  the 
spirit.  The  medical  evangelist,  St.  Luke,  when  describ- 
ing the  resuscitation  of  Jairus'  daughter,  says,  "  Her 
spirit  came  again,  and  she  arose  straightway."  St.  Paul 
describes  the  body  as  a  tent,  or  house,  in  which  the  spirit 
may  be  present  or  absent.  It  is  also  remarkable  that 
the  same  Hebrew  word  which  describes  man  as  a  "living 
soul "  is  applied  to  animals  in  the  same  history  of  crea- 
tion. Gen.  i,  20,  30.  They  also  are  living  souls. 

This  view  of  the  cause  of  life  was  also  held  by  ancient 
Grecian  philosophy.  Aristotle  attributed  organization 
and  vital  actions  to  a  series  of  animating  principles, 
(psychai^)  different  in  each  organized  body,  and  acting 
by  power  derived  from  the  supreme  animating  principle, 
(p/iysis) 


14  THE  SCIENCE  OF  LIFE. 

M  Ciller,  the  father  of  modern  physiology,  substituted 
the  term  "  organic  force"  for  that  of  "animating  princi- 
ple," and  Dr.  Prout  used  the  term  "  organic  agent." 
The  precise  term  employed  is  of  but  secondary  import- 
ance compared  with  the  dualistic  conception,  which  is 
quite  satisfactory  to  the  large  majority  of  thinkers. 

6.  We  shall  be  able  to  appreciate  this  subject  better 
if  we  consider  the  life-history  of  some  simple  animal. 

It  is  well  known  that  infusions  of  vegetable  or  animal 
substances  contain  many  living  forms  of  extreme  sim- 
plicity of  structure,  called  Infusoria.  Many  such  are 
found  in  ponds,  or  running  water,  or  in  the  sea.  A  very 
beautiful  kind  of  Infusoria,  common  among  half-decayed 
leaves,  has  received  the  name  of  Vorticella,  or  bell- 
shaped  animalcule.  There  are  several  species,  the  most 
common  being  known  as  Vorticella  nebulifera.  Take  up 
from  a  pond  a  little  twig,  covered  with  mold  or  mucus- 
like  substance,  and  place  it  under  the  microscope.  In 
all  probability  you  will  see  a  colony  of  Vorticellae, 
(Fig.  i.) 

Each  animalcule  has  a  glassy,  transparent  bell,  with  a 
thick  lip  or  rim,  fringed  with  cilia  or  hair-like  projec- 
tions. These  cilia  are  sometimes  withdrawn,  but  when 
active  vibrate  rapidly,  so  as  to  make  a  sort  of  whirlpool 
in  the  water,  in  the  vortex  of  which  smaller  animals  or 
vegetables  may  be  conveyed  as  food  to  the  interior  of 
the  Vorticella.  A  number  of  pellucid  spots  may  be 
seen  in  the  body  of  each  animalcule,  which  were  for- 
merly regarded  as  stomachs.  Professor  Ehrenberg,  who 
elaborately  investigated  this  class  of  animal  life,  gave 
the  name  Polygastrica  (many  stomachs)  to  those  animal- 


WHAT  is  LIFE?  15 

cules  which  presented  this  appearance.  By  feeding  with 
coloring  matter,  as  carmine  or  indigo,  these  stomachs 
have  been  found  to  be  merely  excavations  in  the  bio- 
plasm, or  living  matter,  which  constitutes  the  body  ot 


r^iG.  i. — a.  Colony  of  Vorticella.  b.  b.  b.  Stages  of  fission,  or  self-division,  c.  A  sep- 
arate individual,  d.  Encysted  state,  e.  Ruptured  cyst  emitting  gemmules  in  a  mass  of 
gelar'ne  or  gum.  f.  Acineta  parasites. 

tht:  animal.  Some  of  these  excavations  are  extempo- 
raneous, but  one  cavity  is  persistent,  and  pulsates  in  a 
peculiar  manner,  so  that  it  has  received  the  name  of 
contractile  vesicle.  Each  glassy  bell  is  attached  to  the 
twig  by  a  slender  thread,  and  usually  swings  to  and  fro 
in  the  water  with  the  thread  or  footstalk  fully  stretched, 
and  the  cilia  moving  rapidly.  Frequently,  however,  and 
especially  on  some  unusual  jar,  or  other  cause  of  alarm, 
the  thread  contracts  in  the  form  of  a  spiral,  and  the  cilia 
are  withdrawn  into  the  substance  of  the  bell. 

These  Infusoria  usually  increase  by  self-division.     The 


1 6  THE  SCIENCE  OF  LIFE. 

globular  bell  becomes  first  flattened,  then  notched,  and 
lastly  divided.  As  soon  as  division  takes  place  there  are 
distinct  motions  in  the  separate  individuals.  In  one  of 
them  the  cilia  are  absorbed,  and  new  cilia  appear  on  the 
side  next  to  the  footstalk.  The  motions  of  the  new  cilia 
form  a  current  sufficient  to  detach  the  newly-formed 
bell,  which  becomes  isolated,  swims  away,  and  develops 
a  new  stalk,  after  fixing  itself  in  a  new  place. 

Another  mode  of  increase  sometimes  occurs,  in  which 
the  animalcule  seems  to  pass  through  a  sort  of  chrysalis 
state.  It  becomes  encysted,  like  the  primitive  forms  of 
vegetables.  It  is  first  rounded,  then  a  sort  of  gelatinous 
secretion  hardens  into  a  case,  protecting  the  interior 
from  antagonizing  cold,  etc. ;  then  the  encysted  body 
breaks  up  into  nuclei,  or  separate  spots,  and  afterward 
into  numerous  gemmules,  or  small  germs,  which  are  set 
free  by  the  bursting  of  the  envelope,  and  swim  away  to 
grow  into  new  individuals. 

During  the  encysting  process  the  Vorticella  often  ap- 
pears like  a  globular  pincushion  with  pins  sticking  in  it. 
This  is  now  known  to  be  caused  by  a  parasite,  the 
Acineta,  which  sends  forth  a  projecting  arm  into  the 
body  of  its  host  to  absorb  its  fluid  nutriment. 

7.  I  have  selected  the  Vorticella  for  a  first  lesson  on 
Biology  because  it  is  quite  common,  and  simple  enough 
for  study.  What  can  we  learn  here  of  life-force?  Is 
there  such  a  thing  as  life-force  ?  Is  there  a  difference 
between  the  living  Vorticella  and  the  dead  twig  it  rests 
upon?  Some  philosophers,  as  we  have  seen,  declare 
that  there  is  no  difference.  The  old  astrologers  used  to 
say  that  all  things  were  living,  and  the  teachers  of  an- 


WHAT  is  LIFE?  17 

cient  magic  and  heathen  philosophy  taught  a  universal 
world-spirit,  which  is  the  life  of  all  things.  To  this  pan- 
theistic theory  the  adherents  of  the  dogma  of  the  me- 
chanical origin  of  the  universe  naturally  gravitate.  It  is 
more  consistent  with  common  sense  and  true  philoso- 
phy, as  well  as  with  the  facts  of  science,  to  maintain  an 
essential  difference  between  the  animate  and  the  inani- 
mate. Can  the  dead  twig  move  spontaneously,  like  the 
living  animalcule  ?  Does  it  assimilate  food  and  repro- 
duce itself  like  the  Vorticella  ?  Or  can  a  dead  animal 
respond  to  natural  stimuli  like  the  living  ?  Not  a  single 
fact  has  been  brought  forward  to  prove  the  identity 
of  the  living  and  the  non-living.  It  is  at  best  on- 
ly a  theory.  "On  the  other  hand,"  says  Dr.  Beale, 
"  thanks  to  the  steady  progress  of  minute  investigation, 
unnoticed  by  popular  writers,  and  perhaps  unknown 
to  them,  the  conclusion  that  life  of  every  kind  is  dis- 
tinct from  ordinary  forces  is  at  this  time  more  strongly 
supported  by  facts,  and  more  firmly  established  than  it 
ever  was."  * 

8.  In  order  to  defend  the  Monistic  philosophy,  and 
the  identity  of  animate  and  inanimate  objects,  some 
argue  that  matter  has  no  existence  as  such,  but  that 
each  atom  is  only  a  center  of  force.  They  thus  repu- 
diate the  charge  of  materialism,  since  they  teach  that 
every  thing  is  spirit.  This  is  a  most  subtle  and  in- 
genious method  of  defense,  yet  is  just  as  baseless  as  the 
grosser  Monism,  which  considers  all  to  be  material. 

Newton's  law,  of  gravity  being  in  direct  ratio  to  the 
mass  of  matter,  that  is,  to  the  number  of  atoms  in  the 

*  Beale's  "  Protoplasm." 
2* 


1 8  THE  SCIENCE  OF  LIFE. 

mass,  proves  atoms  to  be  real  physical  existences.  All 
chemical  science  is  based  on  the  doctrine  that  atoms  and 
molecules  have  weight,  definite  proportions  or  relations, 
and  hence  definite  form.  The  law  of  Avogadro  and  Am- 
pere, as  it  is  called,  that  "  equal  volumes  of  all  substances 
when  in  the  state  of  gas,  and  under  like  conditions,  con- 
tain the  same  number  of  molecules,"  is  confirmed  by  all 
chemical  experiments,  and  necessarily  implies  the  reality 
of  atoms  and  molecules.  Our  own  consciousness  of 
matter,  also,  the  sense  of  otherness  which  pertains  to 
our  knowledge  of  the  objects  of  sense,  is  as  reliable  as 
any  other  knowledge.  We  know  the  otherness,  as  well 
as  the  weight  and  inertia  of  matter  by  the  same  faculties 
by  which  we  know  that  two  and  two  make  four,  and  not 
five.  The  obvious  distinctions  between  the  living  and 
the  not  living  are  all  proofs  of  Dualism. 

9.  As  to  the  theory  that  atoms  have  a  physical  and  a 
spiritual  side,  by  which  opposite  qualities  are  exhibited, 
it  carries  its  own  refutation,  since  it  is  plainly  impossible 
for  a  healthy  mind  to  believe  that  contrary  properties  can 
inhere  in  any  thing  at  the  same  time.  Mr.  Joseph  Cook 
has  pertinently  said  :  "  If  matter  is  a  double-faced  unity, 
having  a  spiritual  and  a  physical  side,  there  must  co- 
inhere  in  one  and  the  same  substratum  extension  and 
the  absence  of  extension,  inertia  and  the  absence  of  iner- 
tia, color  and  the  absence  of  color,  form  and  the  absence 
of  form.  To  assert  that  these  fundamentally  antago- 
nistic qualities  of  matter  and  mind  not  only  inhere,  but 
co-inhere,  in  one  and  the  same  substratum,  is  to  assert 
that  a  thing  can  be  and  not  be  at  the  same  time  and  in 
the  same  sense.  This  limitless  self-contradiction  wrecks 


WHAT  is  LIFE?  19 

in  this  age,  as  it  has  wrecked  in  every  age,  the  pretense 
that  there  is  but  one  substance  in  the  universe.* 

10.  The  continuance  of  life  in  an  organism  composed 
of  new  atoms,  after  the  old  atoms  have  been  cast  off, 
proves  that  the  cause  of  life  does  not  spring  from  the 
atoms  themselves.  An  atom  of  oxygen  or  hydrogen, 
endowed  with  life  to-day,  as  part  of  an  organized  mole- 
cule of  a  Vorticella,  or  as  part  of  our  own  bodies,  may 
be  to-morrow  released  from  its  vital  connections,  and  be 
transported,  as  water  or  air,  to  remote  parts  of  the  globe. 
It  may  form  part  of  the  gigantic  Sequoias  of  the  Sierras, 
the  Cinchona-trees  of  the  Andes,  or  the  Rhododendrons 
of  the  Himalayas.  Before  the  death  of  the  original 
organism,  or  the  tree  it  next  served,  that  atom  of  oxy- 
gen or  hydrogen  may  be  again  discarded,  and  pass  into 
the  germ-cell  of  an  animal,  or  become  part  of  one  of  the 
tissues  of  a  man  in  a  distant  part  of  the  world.  It  is 
evident  that  that  atom  did  not  produce  the  life  with 
which  it  was  first  associated.  What  may  happen  to  one 
atom  may  happen  to  all  the  atoms  of  an  organism.  In 
active  living  beings  this  actually  does  happen,  so  that  all 
the  atoms  of  a  living  body  become  disconnected,  and 
return  to  the  inorganic  world,  or  go  to  serve  other  or- 
ganisms, while  other  atoms  take  their  places,  yet  the 
organized  body  lives  on.  Its  life  depends  not  on  the 
new  atoms,  for  the  body  was  animate  before  these  atoms 
came ;  nor  does  it  depend  on  the  old  atoms,  for  it  con- 
tinues after  they  have  gone.  It  must,  therefore,  depend 
upon  something  different  from  the  material  atoms.  As 
matter  and  spirit  are  the  only  objects  of  thought  pos- 

*  Cook's  "  Biology,"  p.  227. 


20  THE  SCIENCE  OF  LIFE. 

sible  to  us,  and  as  life  does  not  depend  on  matter,  it 
must  depend  on  spirit.  If  existence  and  activity  con- 
tinue after  the  removal  of  the  original  matter,  as  we 
have  seen,  they  may  also  continue  after  all  matter  is 
removed.  Continued  spiritual  existence  is  certainly  con- 
ceivable, and  in  view  of  the  endowment  of  new  atoms 
by  the  vitalizing  force,  we  must  admit  it  to  be  probable, 
even  after  the  material  of  the  organism  is  all  destroyed. 

The  cause  of  life  is  more  than  matter  and  physical 
force.  It  uses  both  matter  and  force  for  its  own  ends 
and  after  its  own  laws.  "  Its  power  of  control  over 
matter  and  physical  laws  proves  its  superiority  over,  and 
its  distinction  from,  matter.  Life  is  matter's  master, 
not  its  slave.  Life  is  a  workman,  a  builder,  a  chemist ; 
and  each  organized  being  has  its  own  appropriate  life, 
the  result  of  the  union  of  the  spiritual  and  the  material 
in  itself."  * 

ii.  The  view  we  have  taken  of  the  difference  between 
the  animate  and  the  inanimate  objects  of  creation  is  one 
which  is  growing  in  favor  with  the  principal  workers  in 
biological  science.  Dr.  Beale's  discoveries  and  gener- 
alizations in  Histology  have  done  much  to  arrest  the 
skeptical  tendencies  of  scientists,  and  in  one  of  Mr. 
Huxley's  latest  utterances  he  acknowledges  that  "  the 
properties  of  living  matter  distinguish  it  absolutely  from 
all  other  kinds  of  things,"  and  that  "  the  present  state 
of  knowledge  furnishes  us  with  no  link  between  the  liv- 
ing and  the  not-living."  f  The  last-named  anatomist 
names  the  distinctive  properties  of  living  matter  as  fol- 

*  "  Agreement  of  Science  and  Revelation,"  by  the  Author. 
f  Huxley's  "Anatomy  of  Invertebrated  Animals." 


WHAT  is  LIFE?  21 

lows:  i.  Its  chemical  composition;  2.  Its  universal  dis- 
integration and  waste  by  oxidation,  and  its  concomitant 
reintegration  by  the  intussusception  of  new  matter ; 
3.  Its  tendency  to  undergo  cyclical  changes. 

Dr.  Beale  shows  that  "  no  relation  can  be  established 
between  the  chemical  or  other  material  properties  of 
different  kinds  of  living  matter  that  will  in  any  way  ac- 
count for  the  different  results  as  regards  development 
and  formation.  The  different  powers  or  properties  of 
the  particles  cannot  be  due  to  difference  of  chemical 
composition.  All  living  particles  consist  of  compara- 
tively few  elements,  and  no  differences  in  the  propor- 
tions of  these  would  enable  us  to  explain  the  different 
results  of  the  act  of  living. 

"  This  wonderful  stuff,  which  is  the  first  state  of  every 
thing  that  has  life,  splits  up  when  it  is  destroyed  into 
a  few  chemical  compounds,  from  the  study  of  which, 
however,  chemists  have  hitherto  failed  to  arrive  at  any 
conclusion  as  regards  the  atomic  relations  of  the  com- 
ponent elements  of  the  matter  during  life.  Neither,  as 
far  as  has  been  ascertained,  is  there  any  constant  rela- 
tion between  the  volume,  or  kind,  or  aggregation  of  the 
matter  which  is  the  seat  of  the  manifestation  of  the  vital 
power  and  the  form  of  living  being  that  is  to  be  evolved 
from  it.  Man's  matter  is  no  more  elaborate,  no  more 
complex,  no  more  beautiful,  than  dog's  matter  or  sheep's 
matter ;  but  it  is  in  the  power,  not  in  the  matter,  that 
we  must  look  for  the  cause  of  the  remarkable  difference 
of  the  results.  Insignificantly  in  matter,  but  transcend- 
ently  in  power,  does  the  man-germ  differ  from  the  dog- 
germ.  Wonderfully  different  power  may  be  transmitted 


22  THE  SCIENCE  OF  LIFE. 

by  particles  of  matter  that  resemble  one  another  in 
every  particular  that  can  be  ascertained."  Again :  "It  is 
by  the  transmission  of  power  to  matter,  rather  than  by 
the  bodily  transference  of  millions  of  particles  of  matter 
having  particular  properties  and  detached  from  matter 
having  similar  properties,  that  inheritable  peculiarities 
are  handed  down  from  parent  to  offspring.  And  it  must 
be  borne  in  mind  that  structure-forming  capacity,  which 
is  not  even  rendered  evident  until  forty  or  fifty  years 
shall  have  passed  since  the  original  germ-speck  origi- 
nated in  the  parent,  may  affect  pounds  weight  of  matter, 
not  one  grain  of  which  will  be  acquired  until  long  after 
every  atom  of  that  primitive  speck  shall  have  ceased  to 
live  and  have  been  removed  from  the  organism.  Matter, 
with  its  forces,  continually  comes  and  goes,  while  power 
only  remains  unimpaired  and  preserves  its  identity. 
Power  has  been  handed  down  —  has  been  transferred 
from  old  particles  to  new  particles  of  matter;  but  the 
original  matter — nay,  in  the  case  of  some  of  the  largest 
animals,  hundreds  weight  of  matter —  must  have  come 
and  gone,  while  the  original  power  remained."  "  Vital 
power  works  according  to  predetermined  order,  and  the 
results  of  its  working  are  seen  in  different  consequences, 
at  different  periods  of  its  action."  "  Vital  power  pre- 
pares for  far-off  events,  and  acts  as  if  phenomena,  not  to 
occur  until  after  the  lapse  of  a  considerable  time,  had 
been  from  the  first  foreseen.  Vital  power  suspends  the 
action  of  chemical  affinity,  and  piles  material  particle 
above  particle,  the  force  of  gravity  notwithstanding."* 
12.  Sometimes  life  remains  dormant  from  lack  of  ap- 

*  "Protoplasm,"  by  Dr.  L.  Beale. 


WHAT  is  LIFE?  23 

propriate  stimuli,  or  conditions,  or  from  sonic  unexplained 
peculiarity.  This  proves  those  philosophers  to  be  in  er- 
ror who  imagine  that  molecular  change  is  essential  to 
life.  The  seed  which  has  been  held  in  the  hand  of  an 
Egyptian  mummy  perhaps  for  thousands  of  years,  re- 
tains the  vital  power,  and  may  sprout  under  favorable 
conditions.  The  wheel  animalcule  (Rotatoria)  has  been 
dried  and  resuscitated  many  times  in  succession,  and 
Messrs.  Drysdale  and  Dollinger  have  proved  that  the 
germs  of  Infusoria  cannot  be  destroyed  by  the  heat  of 
boiling  water,  but  live  when  the  thermometer  shows  a 
heat  of  300°  F.  These  resisting  germs,  floating  in  the 
air,  will  soon  revive  on  the  accession  of  moisture. 

13.  Death  occurs  when  the  cause  of  life  is  removed. 
Life  is  not  synonymous  with  spirit,  but  is  peculiar  spir- 
itual influence  on  matter  ;  the  result  of  the  union  of  cre- 
ated spirits  and  elemental  matter.  When  the  spiritual 
essence  ceases  to  act  upon  the  matter  of  the  organism 
we  say  the  body  is  dead,  and  then  disintegration  and 
chemical  decomposition  succeed.  There  is  a  two-fold 
death  —  the  death  of  the  organism  as  a  whole,  called  so- 
matic, or  bodily  death,  and  molecular  death,  or  the  loss 
of  vital  activity  in  the  molecules  of  the  body.  Life  be- 
gins in  a  single  molecule  of  bioplasm,  and  is  propagated 
as  a  force  more  or  less  modified  from  molecule  to  mole- 
cule, or  from  cell  to  cell,  as  flame  proceeds  from  one 
combustible  substance  to  another,  or  as  magnetism  is 
disseminated  by  the  action  of  a  single  magnet  through 
one  bar  of  steel  after  another. 

Molecular  death  is  a  continual  phenomenon  of  life 
during  its  activity.  It  is  arrested  in  dormant  life,  and 


24  THE  SCIENCE  OF  LIFE. 

is  far  from  being  so  constant  an  attendant  upon  all  the 
actions  of  the  body  as  some  have  taught,  yet  it  goes  on 
with  great  rapidity  and  uniformity.  The  bioplasts,  or 
living  particles,  of  each  tissue  in  the  body  are  changed 
into  formed  material,  and  then  pass  into  decay,  while 
other  bioplasts  take  their  places  and  keep  up  the  active 
dance  of  life.  When  the  spiritual  cause,  or  origin,  of 
vital  phenomena  is  removed,  the  molecular  activities  of 
the  body  do  not  all  cease  at  once,  but  gradually.  Hair 
will  continue  to  grow  on  a  corpse,  and  the  secretion  of 
rattle-snake  poison,  or  of  other  glands,  continues  for  a 
short  time  after  death.  Indeed,  the  circulation  of  blood 
has  been  witnessed  in  a  section  of  mouse's  kidney  some 
time  after  it  had  been  removed  from  the  body.  Yet, 
uninfluenced  by  the  energizing  spirit,  the  vital  activities 
gradually  cease,  and  decomposition  ensues. 

14.  To  return  to  our  example  from  the  Infusoria,  the 
life-history  of  the  Vorticella  demonstrates  both  the  spir- 
itual origin  of  life  and  the  work  of  a  Supreme  Intelli- 
gence. The  evidence  of  design  in  its  construction  is 
quite  apparent.  The  extensile  threads  and  vibsatile 
cilia  have,  plainly  enough,  an  object.  They  subserve 
prehension  of  food  and  the  preservation  of  existence. 
Even  the  contractile  vesicle,  whose  exact  purpose  we  do 
not  know,  impresses  our  minds  with  the  fact  that  it  serves 
some  purpose.  This  design  is  connected  with  some- 
thing different  from  the  material  atoms  of  the  organism, 
but  which  controls  those  atoms,  since  there  is  foresight 
of  future  changes,  and  provision  for  future  changes  in 
the  life-history  which  will  occur  after  the  removal  of  all 
the  present  material.  The  self-division  of  the  Vorticella, 


WHAT  is  LIFE'  25 

the  formation  of  new  cilia,  the  preparation  for  increase 
by  the  encysted  form,  the  division  into  nuclei  and  gem- 
mules,  are  all  examples  of  this,  analogous  to  the  forma- 
tion of  new  structures  in  the  higher  animals.  The  power 
to  produce  these  changes  is  not  material  but  spiritual. 

15.  Thus  our  first  lesson  in  Biology  brings  us  to  the 
confines  of  a  spiritual  world.  We  look  across  the  gulf 
which  philosophy  and  science  cannot  bridge  over  except 
by  revealed  truth,  but  the  telescope  of  faith  can  see  re- 
alities on  the  other  side  as  numerous,  as  diversified,  and 
as  true  as  the  objects  of  sense  which  can  be  weighed  and 
measured  by  our  physical  instruments.  We  see  also  the 
care  and  providence  of  a  Supreme  Creator.  Astronomy 
adds  emphasis  to  the  Psalmist's  declaration,  "The  heav- 
ens declare  the  glory  of  God;  and  the  firmament  showeth 
his  handy-work."  And  Biology  indorses  the  sentiments 
of  his  eloquent  utterances  respecting  living  creatures  : 
"  O  Lord,  how  manifold  are  thy  works  !  in  wisdom  hast 
thou  made  them  all :  the  earth  is  full  of  thy  riches.  So 
is  this  great  and  wide  sea,  wherein  are  things^  creep- 
ing innumerable,  both  small  and  great  beasts.  There 
go  the  ships  :  there  is  that  leviathan,  whom  thou  hast 
made  to  play  therein.  These  all  wait  upon  thee ;  that 
thou  mayest  give  them  their  meat  in  due  season.  That 
thou  givest  them  they  gather :  thou  openest  thine  hand, 
they  are  filled  with  good.  Thou  hidest  thy  face,  they  are 
troubled  :  thou  takest  away  their  breath,  they  die,  and 
return  to  their  dust.  Thou  sendest  forth  thy  spirit,  they 
are  created:  and  thou  renewest  the  face  of  the  earth. 
The  glory  of  the  Lord  shall  endure  forever :  the  Lord 
shall  rejoice  in  his  works." 


26 


THE  SCIENCE  OF  LIFE. 


CHAPTER  II. 

LIVING     MATTER. 

You  may  bury  me  as  you  choose,  if  you  can  only  catch  me.  But  you  will 
not  understand  me  when  I  tell  you  that  I,  Socrates,  who  am  now  speak- 
ing, shall  not  remain  with  you  after  having  drunk  the  poison,  but  shall  de- 
part to  some  of  the  enjoyments  of  the  blest.  You  must  not  talk  about 
burying  or  burning  Socrates,  as  if  I  were  suffering  some  terrible  operation. 
Such  language  is  inauspicious  and  depressing  to  our  minds.  Keep  up  your 
courage,  and  talk  only  of  burying  the  body  of  Socrates  ;  conduct  the  burial 
as  you  think  best  and  most  decent.  —  PLATO'S  Phado. 

1.  THE  only  unexceptionable  characteristic  of  living 
bodies  is  the  possession  of  living  tissue,  or  bioplasm.    This 
may  be  present  alone,  as  in  the  simple  animal  and  veg- 
etable forms,  or  it  may  exist  in  association  with  structure 
which  has  been  formed  by  it,  and  hence  called  formed 
material.     The  bioplasm  is  nourished  by  pabulum  which 
is  generally  furnished  in  fluid  form. 

2.  The  old  division  of  bodies  into  organized  and  un- 

organized—the for- 
mer having  organs, 
or  distinct  parts, 
with  definite  struct- 
ure, and  of  special 
use  —  is  no  longer 
applicable,  since 
there  are  some  liv- 

FIG.  ..-AmcAaprincepsX.so.     In  various  shapes. 


have  no  organs.     The  A  mceba  princcps,  Fig.  2,  one  of  the 
most  elementary  animal  forms,  is  composed  of  a  jelly- 


LIVING  MATTER.  27 

like  homogeneous  bioplasm,  capable  of  indefinite  exten- 
sibility and  of  indefinite  use.  It  is  so  constantly  alter- 
ing its  outline  that  it  does  not  retain  the  same  shape  for 
two  successive  minutes.  It  obtains  its  food  by  flowing 
around  it,  and  digests  by  direct  absorption. 

3.  Of  such  simplicity  of  structure  are  all  the  primitive 
forms  of  vegetable  and  of  animal  life,  while  in  bone,  ( ar- 
tilage,  flesh,  skin,  or  any  other  structure  of  the  higher 
animals,  we  find  such  simple,  jelly-like,  living  matter,  or 
bioplasm,  similar  in  appearance  to  the  Amoeba,  scat- 
tered  in  minute   particles  all  through  the  tissue,  and 
careful   observation   will   show  how  this   living   matter 
is  transformed  into  the  formed  material  of  the  several 
tissues. 

4.  All  animals  and  vegetables  have  originated  from 
minute  particles  of  such  bioplasm.     Every  dog,  horse, 
man,  whale,  jelly-fish,  oak,  cedar,  grass,  sea-weed,  etc., 
began    its  existence  as  a  particle  of  bioplasm.     And 
every  tissue  and  organ,  no  matter  what  its  form  or  func- 
tion, was  built  up  by  similar  living  matter. 

5.  In  the  lowest  type  of  animal  life  (the  Rhizopods) 
the  vital  operations  are  carried  on  without  any  special 
organs,  as  we  have  seen  in  the  Amoeba ;  a  little  particle 
of  jelly-like  bioplasm,  changing  itself  into  a  variety  of 
forms,  laying  hold  of  food  without  members,  swallowing 
it  without  a  mouth,  digesting  it  without   a  stomach, 
moving  without  muscles,  while  the  mere  separation  of  a 
fragment  of  this  jelly,  however  small,  is  sufficient  to 
originate  another  and  independent  living  creature,  re- 
taining, or  rather  repeating,  all  the  characteristic  endow- 
ments of  the  original  mass.      In  the   higher   animals, 


28  THE  SCIENCE  OF  LIFE. 

although  the  first  bioplasmic  particle  subdivides  itself 
into  an  aggregation  of  similar  particles  or  cells,  yet  there 
soon  appears  a  structural  differentiation  of  organs  for 
special  uses,  which  is  more  elaborate  and  heterogeneous 
as  the  type  approaches  the  human  structure.  A  single 
cell  or  living  particle,  however,  in  any  structure  is,  to  all 
intents  and  purposes,  a  living  thing,  and  possesses  pow- 
ers of  assimilation,  growth,  and  reproduction,  altogether 
different  from  the  mineral  or  non-living  body. 

6.  Living  matter,   or   bioplasm,  may  be   considered 
physically   as   a   peculiar    compound    of    the    chemical 
elements  —  carbon,    oxygen,    nitrogen,    and    hydrogen, 
called  by  Mulder  Proteine,  and  by  Mr.  Huxley  and  the 
German  histologists  Protoplasm,  or  the  physical  basis  of 
life.     It  is  nearly  identical  with  Albumen.     So  far  as  is 
known,  this  combination  of  elements  is  always  the  prod- 
uct of  pre-existing,  living  matter.      It  has  never  been 
produced  in  the  laboratory,  and  if  it  were  possible  for  a 
chemist  to  manufacture  albuminoid    matter,   or  proto- 
plasm, it  would  be  dead  protoplasm,  and  not  bioplasm, 
and  would  be  destitute  of  vital  properties.     Other  con- 
ditions are  necessary  to  vital  phenomena  besides  com- 
bination of  material  elements.     Light,  heat,  electricity, 
and  moisture  are   all  necessary  conditions ;    nor  these 
alone,  for  with  all  these  existing  and  active,  the  proto- 
plasm may  not  live.    Some  other  factor  is  essential  to  life 
besides  matter  and  physical  force,  as  we  said  in  the  last 
chapter.     The  term  bioplasm  is  well  applied  to  express 
matter  in  its  living  state,  while  protoplasm  should  be 
restricted  to  the  material  itself. 

7.  The  essential  phenomena  of  living   matter   next 


LIVING  MATTER.  29 

claim   our  attention ;    or,  What  can  a  living  thing  do 
which  the  non-living  cannot  ? 

i.)  All  living  things  have  spontaneous  motion.  The 
non-living  are  passive,  and  only  move  by  the  compelling 
agency  of  some  external  force,  but  the  force  which 
moves  living  matter  is  a  force  which  is  inherent,  and 
cannot  be  explained  by  physical  laws.  Living  matter 
has  primary  energy,  and  can  overcome  inertia,  but  the 
non-living  are  unable  to  originate  motion.  The  spon- 
taneous motions  of  bioplasm,  or  living  matter,  are 
molecular,  amoeboid,  or  wandering. 

a.  Molecular    movement.      This    must    not   be   con- 
founded with  what  has  been  called  Brunonian  motion, 
from  Dr.  Robert  Brown,  who  first  described  it  in   1827. 
The  latter  is  a  sort  of  vibration  in  small  particles  sus- 
pended in  fluid,  and  is  supposed  to  be  caused  by  cur- 
rents formed  by  heat  or  evaporation.     In  the  molecular 
movements  of  bioplasm  each  particle  of  the  mass  seems 
to  be  independent  of  the  rest.     As  the  passengers  in  a 
crowded  street  may  go  the  full  length  of  the  street,  or 
turn  back,  or  stop  and  double  as  many  times  as  they 
wish,  so  do  the  particles  move  in  the  mass  of  bioplasm. 
Up,  down,  across,  backward,  and  in  all  directions— even 
through  each  other — do  these  molecules  move,  each  im- 
pelled by  its  own  inherent  energy.* 

b.  Amoeboid  movement  receives  this  name  from  its 
resemblance  to  the  notions  of  the  Amoeba,  described  in 
the  present  chapter,  Sec.  2.     The  shape  is  continually 
changing,  by  a  portion  of  the  body  being  projected  from 
the  mass,  or  retracted,  or  altered  in  form. 

*  Strieker's  "  Manual  of  Histology." 


30  THE  SCIENCE  OF  LIFE. 

c.  Wandering  movement  is  a  modification  of  the  latter 
form.  A  portion  of  the  bioplasm  is  projected  forward, 
and  along  this  temporary  arm,  or  bridge,  the  semi-fluid 
molecules  flow  along,  and  accumulate  at  the  farthest 
end.  In  this  manner  the  white  cells  of  blood,  which  are 
particles  of  bioplasm,  wander  out  of  the  vessels,  perhaps 
by  means  of  stomata,  or  holes,  in  the  sides  of  the  vessels, 
into  those  tissues  of  the  body  where  they  are  needed, 


FIG.  3. — Clot  of  Frog's  Blood,  with  Migrating  White  Blood-cells. 

Fig.  3.      These   motions   are  wholly  unlike  any  which 
occur  in  lifeless  material. 

2.)  Another  essential  property  of  bioplasm  is  growth. 
The  term  growth  does  not  mean  accretion  or  addition 
of  material,  nor  increase  of  size.  A  piece  of  chalk,  or  a 
bank  of  mud,  or  any  non-living  thing,  may  increase  in 
size  by  additions  to  its  material.  Growth  in  a  living 
thing  is  different.  It  is  enlargement  by  nutrition,  and 
depends  on  inherent  motion.  In  Chap.  I,  Sec.  13,  it  was 
stated  that  hair  would  grow  on  a  corpse,  but  the  term 
grow  was  used  in  a  popular,  and  not  scientific,  sense. 
Hair  is  not  a  living  part  of  the  body.  Hair  or  nails  may 
be  cut  or  destroyed  without  sensation  or  impairment  of 
the  body.  They  consist  of  scales  of  formed  material, 


LIVING  MATTER.  31 

pushed  forward  by  the  growth  of  bioplasm  behind  them. 
If  you  pull  out  a  hair  or  nail,  you  reach  the  quick — that 
is,  the  living  or  sensitive  part.  We  thus  see  that  some 
parts  of  our  body  are  alive,  and  others  in  a  non-living 
state.  The  formed  portions  never  grow,  but  the  bio- 
plasm, or  living  matter,  grows.  The  growth  of  living 
matter  is  by  appropriation  and  transformation.  Bio- 
plasm "  alone,  of  all  matter  in  the  world,  moves  toward 
lifeless  matter,  incorporates  it  with  itself,  and  communi- 
cates to  it,  in  some  way  we  do  not  in  the  least  under- 
stand, its  own  transcendentally  wonderful  properties." 
This  motion  and  incorporation  and  endowment  consti- 
tute growth. 

"  The  rootlets  of  the  plant  extend  themselves  into  the 
soil  because  the  living  matter  at  their  extremities  moves 
onward  from  the  point  already  reached.  The  tree  grows 
upward  against  gravity  by  virtue  of  the  same  living 
power  of  bioplasm.  In  every  bud  portions  of  this  living 
matter  tend  to  move  away  from  the  spot  where  they 
were  produced,  and  stretch  upward  and  onward  in  ad- 
vance. No  tissue  of  any  living  animal  could  be  formed 
unless  the  portions  of  bioplasm  moved  away  from  one 
another."  * 

3.)  Living  matter  has  also  the  power  of  nutrition,  or 
assimilation  by  selection.  As  this  is  connected  with 
growth,  we  might  have  considered  it  under  that  head, 
but  since  writers  of  the  mechanical  or  materialistic  school 
attempt  to  account  for  it  on  physical  or  chemical  princi- 
ples, we  deem  it  best  to  examine  it  separately. 

The  non-living  always  enlarges  by  accretion  from  sirn- 

*  Beale's  "  Bioplasm." 


32  THE  SCIENCE  OF  LIFE. 

ilar  material ;  the  living  tissue  takes  into  its  interior  ma- 
terial which  it  transforms  out  of  pabulum,  which  is  foreign 
to  its  own  structure,  while  at  the  same  time  it  discards 
such  molecules  or  atoms  as  are  unfit  for  further  use. 

The  chemical  composition  of  the  various  tissues  of  the 
body  cannot  be  found  in  the  blood,  or  pabulum,  which 
nourishes  the  tissues,  but  results  from  metamorphosis,  or 
transformation,  by  means  of  the  bioplasts.  Endosmose, 
or  the  physical  property  by  which  fluids  pass  through 
membranes,  or  gummy  matters,  will  not  account  for  it, 
since  in  the  latter  there  is  no  change  of  material,  while 
in  nutrition  there  is  rearrangement  of  the  atoms  in  the 
tissue-molecules. 

Nutrition  has  sometimes  been  compared  with  crystalli- 
zation, but  crystallization  is  a  deposit  of  material  from  a 
solution  of  similar  substance,  and  is  altogether  different 
from  nutrition  by  transformation  and  selection. 

Nutrition  has  also  been  compared  with  a  chemical 
phenomenon  called  catalysis.  In  this,  chemical  change 
takes  place  because  of  the  presence  of  a  substance  which 
remains  itself  unaffected,  as  when  spongy  platinum  in- 
duces the  combination  of  oxygen  and  hydrogen  gases. 
In  catalysis  the  third  substance  neither  gives  nor  takes 
from  the  excited  body,  but  in  nutrition  the  living  matter 
itself  selects  appropriate  chemical  elements  from  its  pab- 
ulum, dissolving  their  former  affinities,  and  recembining 
them  in  a  manner  which  no  non-living  substance  can  do. 
There  is  no  third  substance  present  which  is  known  to 
us,  and  all  the  phenomena  are  peculiar  to  living  matter, 
or  bioplasm. 

4.)  Bioplasm  can  also  transmit  vital  power  to  its  prog- 


LIVING  MATTER.  33 

eny.  This  property  will  be  considered  more  in  detail  in 
the  next  chapter,  on  Parentage. 

8.  The  peculiar  relations  and  changes  of  the  chemical 
elements  in  bioplasm  prove  it  to  possess  some  power 
different  from  not-living  matter,  whose  actions  or  results 
no  chemistry  can  predict.  We  have  said  that  bioplasm 
consists  chejmically  of  oxygen,  hydrogen,  carbon,  and 
nitrogen.  Other  unessential  elements  may  also  be  pres- 
ent in  some  cases.  But  we  cannot  tell  how  these  ele- 
ments are  combined,  if,  indeed,  they  are  combined  at  all 
in  the  proper  sense  of  that  word.  As  all  bioplasm  pre- 
sents the  same  appearance,  although  differently  formed 
material  results  from  its  transformation  —  different  in 
physical  properties  and  in  chemical  composition  —  as 
muscle,  nerve,  bone,  etc.,  it  is  probable  that  the  ele- 
ments do  not  combine  at  all  as  in  inorganic  matter,  but 
that  the  ordinary  affinities  are  suspended  or  modified 
by  vitality. 

Bioplasm  is  a  semi-fluid  substance,  yet  it  will  not 
freeze  at  32°  F.,  as  water  does,  showing  that  in  this  re- 
spect it  is  different  from  water. 

Bioplasm  is  in  a  state  of  constant  molecular  change, 
or  unstable  equilibrium,  since  it  is  constantly  receiving 
pabulum  and  transforming  itself  into  formed  material, 
so  that  it  is  doubtful  if  chemical  combination  is  possible 
during  life,  the  atomic  activities  being  too  transitory  for 
combination. 

When  change  takes  place  from  bioplasm  into  formed  ma- 
terial combination  occurs,  but  the  formed  material  is  not 
living  tissue,  or  bioplasm.  The  life  is  gone.  It  is  dead, 
as  if  it  had  never  formed  part  of  an  organism,  although 


34  THE  SCIENCE  OF  LIFE. 

it  may  have  acquired  special  properties,  as  the  elasticity 
of  muscle,  or  the  conducting  power  of  nerve  tissue. 

If  the  change  referred  to  occurs  suddenly,  that  is,  if 
the  life  of  bioplasm  is  suddenly  destroyed,  the  result  is 
water,  albumen,  fat,  and  sometimes  fibrin,  and  certain 
salts,  as  chloride  of  sodium,  etc. 

In  slower  transformations,  which  are  equivalent  to 
slow  molecular  death,  different  materials  result,  as  fat, 
sugar,  milk,  biliary  acids,  etc.  Free  oxygen  is  some- 
times absorbed,  and  very  complex  compounds  result, 
often  baffling  analysis. 

Physiological  Chemistry  has  traced  many  of  the  re- 
sults of  changes  in  formed  material,  but  the  composition 
and  physical  surroundings  of  germinal  or  living  matter 
will  not  indicate  the  nature  of  its  transformations  nor  its 
function.  No  one  can  tell  whether  a  particular  bioplast 
belongs  to  a  vegetable  or  an  animal,  whether  it  will  form 
ar  eye  or  a  finger,  a  nerve  or  a  piece  of  bone,  nor  whether 
its  function  shall  be  secretive,  excretive,  elastic,  or  con- 
ductive. Nothing  but  observation  can  tell  its  future  life- 
history. 

9.  Although  all  bioplasm  has  powers  or  endowments 
which  transcend  all  physics  and  chemistry,  and  which 
can  only  be  accounted  for  by  that  dualistic  philosophy 
which  acknowledges  the  reality  of  both  matter  and 
spirit,  yet  "  all  flesh  is  not  the  same  flesh."  There  is  an 
original  and  essential  distinction  between  bioplasts. 
The  bioplasm  of  a  fungus  never  produces  a  fish,  nor  that 
of  a  butterfly  a  man.  This  will  be  fully  discussed  in  the 
chapter  on  Parentage.  Yet  it  is  no  easy  task  to  dis- 
criminate between  living  forms,  especially  in  what  are 


LIVING  MATTER.  35 

called  the  lower  orders.  It  is  difficult  to  distinguish  in 
all  cases  between  animals  and  plants.  In  the  simpler 
kinds  the  characters  touch  and  dissolve  into  each  other, 
so  that  no  exclusive  definition  is  possible.  Some  natur- 
alists think  that  there  are  organisms  which  at  one  period 
of  life  are  vegetable,  and  at  another  animal. 

10.  If  we   consider   their   origin,   both   animals   and 
plants  begin  life  as  a  small    particle  of  bioplasm.     In 
plants  this  forms  an  ovule,  with  wall  of  cellulose,  and 
in  animals  it  becomes  an  ovum,  or  egg,  with  wall  of  al- 
buminous matter. 

11.  As   to   form,   we    have  no   means    of    separating 
animals  and  plants.      The   zoospores  of  Algae  are  like 
Infusoria.    Sea-mat 

(Flustra)  and  Sea- 
moss  (Fig.  4)  (Poly- 
zoa)  are  like  Sea- 
weeds, (Algae,)  Cor- 
als and  Actiniae  are 
like  flowers. 

12.  In    chemical 
composition,    as    a 
rule,  plants  are  des- 
titute of,   and   ani- 
mals    are     largely 

Supplied      With       ni-  F,G.4.-SertulariaOPerculata. 

trogen.  Yet  there  are  some  animal  structures  without 
nitrogen,  and  some  vegetable  structures  with  it.  Cellu- 
lose, (woody  fiber,)  generally  found  in  vegetables,  is 
wanting  in  the  Fungi,  and  is  found  in  the  covering  of 
Ascidians,  (Sea-squirts.)  Starch,  under  the  name  of 


36  THE  SCIENCE  OF  LIFE. 

Glycogen,  is  found  in  the  liver  and  in  the  brain.  Chlo- 
rophyll, which  makes  the  leaves  of  vegetables  green, 
is  found  among  animals,  as  in  Stentor,  (the  trumpet- 
shaped  animalcule,)  and  in  Hydra  viridis,  (the  green 
hydra.) 

13.  As  to  locomotive  power,  bioplasm  is  essentially 
active,  as  I  have  described,  both  in  plants  and  animals. 
The  zoospores  of  Algae  are  covered  with  cilia,  and  move 
in  water  like  animalcules.     Motion  is  common  among 
Diatoms,    Desmids,    Oscillatoria,    and  other   classes   of 
plants,  while  Sponges,   Corals,   Oysters,  and    Barnacles 
are  largely  destitute  of  locomotive  power. 

14.  With  respect  to  food,  plants  live  generally  on  min- 
eral or  inorganic  matter,  chiefly  water,  carbonic  acid,  and 
ammonia,   while    animals    require    ready-made   organic 
compounds  to  support  life.     Thus  plants  manufacture 
and   animals    consume    organic   pabulum.     Yet    Fungi, 
which   are   generally  classed    with    vegetables,    feed    as 
animals  on  organic  matters,  and  insectivorous  plants,  as 
Darwin  has  shown,  feed  on  animals. 

15.  Animals    generally  possess    sensation,   conscious- 
ness, and  volition,  yet  there  is  a  kind  of  sensation  in  the 
sensitive  plant,  Venus'  fly-trap,  etc.,  and  something  like 
volition  in  zoospores,  or  they  would  often  collide  in  the 
active   dance  they  keep   up.     Plants  need   rest   as  well 
as  animals.     Both  have  their   epidemics,  poisons,  and 
remedies. 

16.  If  we  admit  a  dualism,  or  spiritual  cause  of  life,  in 
vegetables,  as  well  as  in  animals,  it  does  not  prove  them 
immortal.      Immateriality  does  not  imply  immortality. 
Existence,  spiritual  or  material,  depends  on  the  will  of 


ER.  V 


LIVING  MATTE 

the  Creator,  and  we  can  only  know  the  future  as  he  has 
revealed  it. 

"  Heaven  from  all  creatures  hides  the  book  of  Fate, 
All  save  the  page  revealed  —  the  present  state." 

17.  Our  study  thus  far  impresses  us  not  only  with  the 
truth  that  all  living  things  manifest  a  dualism,  but  also 
that  all  living  are  intimately  related.  Not  that  all  come 
from  a  single  germ,  or  from  a  few  germs,  but  that  ani- 
mals and  plants  form,  after  some  sort,  a  common  family. 
From  the  great  Father  and  Fountain  of  life  all  living 
things  proceed,  and  their  existence  and  endowments  are 
according  to  his  will.  Immaterial,  or  spiritual  existen- 
ces weave  for  themselves  a  beautiful  garment  from  the 
inorganic  world.  The  plant  bioplasm  appropriates  min- 
eral matter,  with  carbonic  acid,  water,  and  ammonia, 
and  by  a  wonderful  vital  chemistry  transforms  it  into 
organic  compounds,  as  starch,  sugar,  gum,  albumen,  etc. 
These  compounds  afford  pabulum  to  animal  bioplasm, 
and  are  transformed  to  blood,  muscle,  nerve,  and  other 
complex  animal  substances.  After  these  transformed 
products  have  served  the  purposes  of  animal  life  they 
are  discarded,  and  return  again  to  the  mineral  world. 
Thus  the  wonderful  wheel  of  life  revolves  from  age  to 
age  under  the  watchful  care  of  divine  Providence. 

1  8.  The  intimate  relations  of  living  things  may  find  a 
mathematical  illustration  in  the  logarithmic  spiral,  such 
as  is  described  by  a  ship  sailing  N.  E.  at  an  angle  of  60° 
from  the  pole.  It  is  the  spira  mirabilis  of  Jas.  Bernou- 
illi,  who  desired  one  to  be  engraved  on  his  tomb,  with 
the  motto  :  *"  Eadem  mutata  resurgo  "  —  "  I  rise  the  same, 
though  changed."  It  is  a  spiral  which  has  the  same 


38  THE  SCIENCE  OF  LIFE. 

character  in  all  its  parts,  and  which  may  continually  de- 
crease in  the  size  of  its  windings  without  coming  to  a 
point,  or  increase  the  number  of  its  convolutions  to  in- 
finity. Such  a  spiral  may  illustrate  the  continuity,  yet 
varying  amplitude,  of  creation.  We  may  trace  the  pro- 
gressive windings  of  creative  power  from  the  motions  of 
inorganic  bodies  in  space  to  the  motions  of  bioplasm  in 
the  vegetable  world  and  to  the  higher  nerve-structures 
of  animal  life.  In  all  organic  matter  we  see  the  work- 
manship of  the  same  Great  Artist : 

"  Lo  !  on  each  seed  within  its  slender  rind 
Life's  golden  threads  in  endless  circles  wind  ; 
Maze  within  maze  the  lucid  webs  are  rolled, 
And,  as  they  burst,  the  living  flame  unfold." 

In  exact  truth,  however,  each  widening  circle  of  crea- 
tion exhibits  some  new  and  higher  form  of  creative 
power  and  skill.  The  circle  widens,  and  is  also  in  an- 
other plane.  Something  has  pushed  forward  the  center. 
Every  spiral  requires  a  progressive  force,  as  well  as  a 
centripetal  and  centrifugal  one.  Each  specialization — 
either  elevation  of  type  or  specific  difference — involves 
new  force-expenditure.  Certain  factors  have  been  suc- 
cessively added.  First,  we  find  inorganic  matter,  of 
many  kinds,  or  of  a  single  kind.  Next,  the  physical 
forces,  so-called,  but  really  the  activity  of  a  personal 
Creator  on  the  matter  he  has  formed.  Then  we  find 
life,  or  the  activities  in  matter  of  created  spirits  in  most 
wonderful  gradation.  Rising  to  another  plane  we  find 
added  to  this  life  mind-force,  or  intelligence.  Still 
higher  we  find  spirit,  properly  so-called,  possessed  with 
moral  properties,  giving  dignity  to  men  and  angels. 


LIVING  MATTER.  39 

Yet  the  spiral  is  not  broken,  it  is  but  expanded,  and  the 
analogies  and  relations  have  a  distinctive  similarity, 
since  they  are  equally  the  work  of  one  God  and  Creator 
of  all.  As  the  physical  forces,  by  attraction  and  vibra- 
tion, and  conservation,  arrange  the  cosmos,  or  physical 
universe,  so  the  various  bioplasts  weave  the  living  tis- 
sues for  the  living  creature — the  microcosmos — and  so 
the  conscious  acts  of  our  spirits  weave  the  character  of 
our  future  life. 


40  THE  SCIENCE  OF  LIFE. 


CHAPTER  III. 

PARENTAGE. 

We  must  get  rid  of  all  these  complications  of  an  erring  philosophy,  this 
floating  chaos  of  mist  and  phantasms,  and  return  to  the  Natural  Realism, 
which  all  men  have  been  learning  from  their  first  hours  of  childhood,  and 
can  never  unlearn,  before  a  science  of  Physics  can  be  really  founded.  Its 
first  principle  is  that  we  are  real  persons,  living  amid  a  real  world  of  ma- 
terial objects  distinct  from  ourselves.  And  this  double  truth  leads  upward 
to  One  who  is  the  cause  both  of  matter  and  mind,  the  Supreme  Reality, 
who  dwells  in  light  inaccessible,  but  who  can  reveal  himself,  and  has  re- 
vealed himself,  in  love  and  mercy  to  the  souls  he  has  made.  —  Modern 
Physical  Fatalism,  by  T.  R.  BlRKS. 

1.  Two  theories  divide  the  learned  world  respecting 
the  genesis  of  living  things ;  the  doctrine  of  parentage, 
or  the  descent  from  living  creatures  each  created  "  after 
his  kind,"  and  the  theory  of  spontaneous  generation  of 
the  living  from  the  non-living,  and  the  transmutation  of 
one  kind  of  living  beings  into  another.     The  first  theory 
is  sometimes  called  the  doctrine  of  Creation,  the  latter 
that  of  Evolution. 

2.  The  word  Evolution  simply  means  to  unfold,  and 
may  be  used  to  express  the  life-history  of  individuals  or 
of  species,  or  the  development  of  the  plans  of  the  Crea- 
tor in  the  natural  world.      To  such  a  meaning  there 
would  be  no  objection  by  any  one,  but  as  it  is  generally 
understood  to  mean  the  mechanical  or  monistic  view  of 
the  universe,  which  ignores  a  Creator,  and  teaches  the 
eternity  of  substance,  the  invariability  of  law,  and  the 
transmutation  of  living  beings,  its  use  should   be  re- 


PARENTAGE.  41 

striated  to  that  view.     Any  other  application  of  it  leads 
to  confusion  of  thought. 

3.  There  is  nothing  new  in  the  modern  doctrine  of 
Evolution.     Among  the  Greeks,  Leucippus,  Democritus, 
and  Epicurus  taught  that  all  forms  and  phenomena  came 
from  the  spontaneous  motions  of  atoms,  and  this  view, 
in  all  probability,  was  a  product  of  older  Indian  pan- 
theism. 

Modern  upholders  of  transmutation  differ  from  each 
other  greatly  in  the  details  of  the  theory.  Some  are 
atheistic,  or  agnostic,  leaving  the  Creator  entirely  out  of 
view.  Among  these,  some  teach,  like  Lamark,  the  self- 
elevation  of  species  by  appetency,  or  desire,  use,  and 
effort.  Others,  as  Darwin,  Haeckel,  and  many  late  writ- 
ers, teach  what  is  called  natural  selection  with  spontane- 
ous variability,  or  the  survival  of  the  fittest.  Others 
again,  as  Draper  and  Spencer,  teach  modification  of 
species  by  the  surrounding  conditions.  Some  evolution- 
ists are  deistic,  like  Owen  and  Mivart,  and  teach  a  pre- 
ordained succession,  under  internal  force  or  innate 
tendency ;  or,  as  Morell  and  Murphy  argue,  evolution 
by  unconscious  intelligence.  In  opposition  to  these 
views  the  majority  of  naturalists  of  this  and  the  past  age 
hold  to  the  doctrine  of  parentage,  and  deny  the  change 
or  transmutation  of  species,  although  admitting  a  cer- 
tain amount  of  physical  variability,  producing  races  or 
varieties.  Among  these  may  be  named  Linnaeus,  Cuvier, 
Agassiz,  Dana,  Guyot,  M'Cosh,  Balfour,  Dawson,  Milne, 
Edwards,  and  Seelye. 

4.  The  acknowledged  ability  of  Agassiz  in  regard  to 

all  matters  connected  with  natural  science  entitle  his 

'4* 


42  THE  SCIENCE  OF  LIFE. 

opinions  to  careful  consideration.  He  says  :  "  It  is  my 
opinion  that  naturalists  are  chasing  a  phantom,  in  their 
search  after  some  material  gradation  among  created  be- 
ings, by  which  the  whole  Animal  Kingdom  may  have 
been  derived  by  successive  development  from  a  single 

germ,  or  from  a  few  germs It  is  contradicted  by  the 

facts  of  Embryology  and  Palaeontology,  the  former  show- 
ing us  norms  of  development  as  distinct  and  persistent 
for  each  group  as  are  the  fossil  types  of  each  period  re- 
vealed to  us  by  the  latter."  "  If  they  are  linked  together 
as  a  connected  series,  then  the  lowest  Acaleph  should 
stand  next  in  structu/e  above  the  highest  Polyp ;  and 
the  lowest  Echinoderm  next  above  the  highest  Acaleph. 
So  far  from  this  being  the  case,  there  are,  on  the  con- 
trary, many  Acalephs  which,  in  their  specialization,  are 
unquestionably  lower  in  the  scale  of  life  than  some 
Polyps,  while  there  are  some  Echinoderms  lower  in  the 
same  sense  than  many  Acalephs."  He  shows  that  the 
same  principle  applies  to  classes  in  other  types:  "There 
are  some  members  of  the  higher  classes  that  are  inferior 
in  organization  to  some  members  of  the  lower  classes." 
The  same  thing  is  true  in  Embryology :  "  A  Vertebrate 
never  resembles  at  any  stage  of  its  growth  any  thing  but 
a  Vertebrate,  or  an  Articulate  any  thing  but  an  Articu- 
late, or  a  Mollusk  any  thing  but  a  Mollusk,  or  a  Radiate 
any  thing  but  a  Radiate."  Geologically,  also,  we  see  no 
transition  between  types.  "  In  the  earliest  fossiliferous 
strata  there  were  the  three  classes  of  Radiates,  two  of 
the  classes  of  Articulates,  and  one  of  the  classes  of  Ver- 
tebrates." The  Geographical  Distribution  of  animals 
proves  the  same  thing.  Thus  Agassiz  proves  that  the 


PARENTAGE.  43 

Series  of  Rank,  of  Growth,  of  Time,  and  of  Geograph- 
ical Distribution  all  show  that  there  is  no  such  gradation 
as  transmutation  implies,  and  that  the  connection  be- 
tween different  kinds  of  living  things  is  not  a  material 
connection,  but  only  an  intellectual  one,  indicating  the 
plan  of  the  Great  Architect.* 

5.  In  all  forms  of  life  which  have  yet  come  under 
human  observation,  the  origin  has  not  been  by  transmu- 
tation, but  by  parental  derivation.     Animals  and  vege- 
tables all  come  from  parents  of  similar  organization.     If 
ever  transmutation  was  the  law  of  origin,  it  has  been 
changed,  and  the  law  of  parentage  is  now  supreme.    But 
a  change  of  law  is  inconsistent  with  the  theory  of  evolu- 
tion.    Unless  the  law  had  been  changed,  species  would 
still  originate  by  transmutation,  if  ever  they  had  such 
origin.      Such  transmutation  has  never  been  observed. 
The  Egyptian  monuments  prove  that  the  animals  of 
earliest    history    remain    unchanged,   and    Agassiz    has 
shown  from  the  coral  reefs  in  Florida  that  the  animals 
of  the  Gulf  of  Mexico  remain  the  same  as  when  these 
deposits  began.     Even  the  varieties  which  man  secures 
by  "  artificial  selection  "  revert  to  the  original  type  when 
the  modifying  circumstances  are  removed.     Transmuta- 
tion has  not  a  single  fact  to  prove  it.     At  best  it  is  but 
a  theory,  and  one  which  all  the  facts  known  render  most 
improbable. 

6.  The  geological  evidence  shows  the  entire  absence 
of  intermediate  varieties  between  species,  which  inter- 
mediate forms  Mr.  Darwin  himself  admits  to  be  neces- 
sary to  establish  his  theory  of  natural  selection.     He 

*  Agassiz,  "  Methods  of  Study  in  Natural  History  " 


44  THE  SCIENCE  OF  LIFE. 

claims  that  the  geologic  record  is  defective,  and  that 
when  it  is  better  known  it  will  exhibit  these  forms.  But 
among  more  than  30,000  species,  many  of  them  repre- 
sented by  thousands  of  individuals,  some  of  the  interme- 
diate forms  would  occur,  if  any  ever  existed.  Professor 
Pfaff  has  shown  the  improbability  of  the  terminal  links 
only  of  the  chain  being  preserved  by  applying  the  calcu- 
lus of  probabilities.  If  100  individuals  of  each  species 
have  been  found,  and  10  intermediate  varieties  existed, 
(a  smaller  number  than  Darwin  claims,)  the  probability 
against  the  exclusive  appearance  of  distinct  species  is  as 
1:10™!,  (i:i  with  100  ciphers  annexed.*)  Professor 
Marsh  claims  to  have  discovered  apparently  intermedi- 
ate forms  between  the  Palaeotherium  and  the  horse,  but 
the  proof  that  the  Palaeotherium,  or  the  bones  referred 
to,  belonged  to  the  progenitors  of  the  horse  has  not 
been  shown,  any  more  than  the  juxtaposition  of  bones 
of  the  horse,  the  zebra,  and  the  ass,  would  prove  them 
to  be  derived  from  each  other.  If  it  were  proven,  al- 
though it  would  show  great  variability  in  that  species,  it 
would  not  establish  transmutation. 

7.  Geology  shows  that  some  of  the  first  forms  of  life 
are  also  the  latest,  as  the  corals.     If  transmutation  be 
true,  in   the   struggle  for   existence  they  should   have 
disappeared  by  being  changed  into  something  higher. 
That  they  have  not  makes  against  Evolution. 

8.  Believers  in  transmutation  claim  that  all  living  came 
into  existence  by  the  gradual  modification  of  a  primitive 
germ,  and  they  find  plausibility  for  this  in  the  develop- 
ment of  a  single  bioplast  into  the  various  tissues  of  an 

*  Johnson's  "  Cyclopedia,  Art.  Darwinism." 


PARENTAGE.  45 

animal.  Another  analogy  is  found  in  the  development 
of  the  embryo.  As  the  tadpole  is  first  a  fish,  and  then 
a  tailed  amphibian  with  lungs  and  gills,  before  it  be- 
comes a  frog,  so  they  deem  that  the  history  of  the 
embryo  recapitulates  the  transformations  of  the  species. 
This  sort  of  theorizing  has  given  rise  to  numerous  efforts 
to  arrange  the  family  tree  of  each  species — a  branch  of 
biological  speculation  termed  Phytogeny — and  examples 
of  it  may  be  found  in  Darwin,  Haeckel,  etc.  Mr.  Hux- 
ley, although  a  believer  in  Evolution,  declares  that  such 
summaries  of  descent  are  little  better  than  guess-work.* 
9.  Many  instances  of  complicate  and  perfect  structure 
occur  both  in  the  vegetable  and  animal  kingdoms  which 
have  no  similar  structure  preceding  nor  following  them. 
No  scheme  of  evolution,  nor  survival  of  the  fittest,  can 
account  for  them.  The  mechanism  of  the  leaf  of  Venus's 
fly-trap,  and  of  Nepenthes,  the  nettling  threads  of  Hy- 
droid  polyps,  and  the  peculiar  disk-like  hairs  on  the 
thigh  of  the  male  water-beetle,  (Dytiscus  marginalis,)  are 
a  few  out  of  almost  numberless  instances  of  this  fact. 
The  most  perfect  dental  apparatus  in  the  animal  king- 
dom, the  teeth  of  Echinus,  called  Aristotle's  lantern,  is 
also  the  first  to  appear,  if  we  trace  animal  life  from  its 
simplest  forms,  and  there  is  nothing  like  it  elsewhere. 
Like  Melchizedek  among  priests,  it  has  no  predecessor 
and  no  successor.  Its  form  and  arrangement  are  a  pro- 
test against  the  theories  of  material  development.  In 
the  Rotifer,  again,  the  typical  form  and  structure  of  the 
teeth  are  entirely  different,  being  an  anvil  and  two  ham- 
mers. In  the  Gasteropods  they  are  spiny  tongues. 

*  "Anatomy  of  Invertebrated  Animals." 


46  THE  SCIENCE  OF  LIFE. 

10.  Evolutionists  find  it  difficult,  if  not  impossible,  to 
account  for  the  first  origin  of  living  matter.     The  bold- 
est and  most  logical  among  them  maintain  that  it  began 
spontaneously  out  of  non-living  matter.     Some,  like  Sir 
W.  Thompson,  suppose  that  the  germs  of  living  things 
were  transported  to  our  globe  from  some  other.    Others, 
as  Darwin,  hold  to  the  creation  of  a  single  germ,  or  a 
few  germs,  from  which  all  have  developed.     The  doc- 
trine of  the  spiritual  origin  of  living  things  is  beset  with 
no  such  difficulties  as  the  mechanical  theory.     While  it 
admits  a  unity  of  plan  resulting  from  the  superintending 
intelligence  of  an  all-wise  Creator,  it  sees  in  living  things 
a  true  diversity  also.     It  is  hard  to  imagine  how  a  nat- 
uralist can  think  of  "  differentiation  "  without  acknowl* 
edging  a  cause  of  variety  ab  extra,  (from  without.) 

11.  The   evidence   adduced   in  favor  of  spontaneous 
generation  is  always  of  one  kind.     A  quantity  of  animal 
or  vegetable  infusion  is  boiled  in  a  flask,  which  is  then 
hermetically  sealed.     After  a  time  minute  forms  of  life 
are  found  on  a  microscopic  examination  of  the  fluid.     It 
is  taken  for  granted  that  all  living  germs  are  destroyed 
by  boiling  water,  and  that  therefore  the  organisms  seen 
after   a   few   days   are   developed   spontaneously.      But 
Messrs.  Dollinger  and  Drysdale  have  shown  that  some 
germs  remain  alive  after  exposure  to  a  temperature  of 
300°  F.,  and  Pasteur  has  found  that  stopping  the  necks 
of  the  flasks  with  cotton  wool,  so  as  to  filter  the  air 
from  all  germs,  prevents  the  appearance  of  Infusoria,  as 
well  as  of  decay,  in  fluids  well  adapted  to  such  organ- 
isms.    Professor  Tyndall  has  also  experimented  with  a 
great  variety  of  fluids  in  air  so  deprived  of  floating  germs 


PARENTAGE.  47 

as  to  be  optically  pure,  and  has  had  similar  results.  So 
that  we  may  consider  the  question  to  be  scientifically 
settled,  and  that  all  living  beings  come  from  similar 
parentage,  or,  as  Virchow  expresses  it,  "  omnis  cellula 
e  cellula"  (every  cell  is  from  a  cell.) 

12.  Parentage  is  of  two  kinds,  sexual  and  non-sexual. 
In  the  first,  we  sometimes  find  the  sexes  distinct,  as  in 
the  higher  animals,  and  sometimes  united  in  the  same 
Individual,  as  in  the  stamens  and  pistils  of  most  flowers, 
and  as  in  some  animal  forms. 

Non-sexual  generation  is  seen  mostly  in  the  simpler 
forms  of  animal  and  vegetable  life,  and  as  it  throws  light 
on  many  of  the  phenomena  of  nature  which  would  other- 
wise be  obscure,  we  notice  this  form  of  reproduction  here 
in  a  general  way,  reserving  special  instances  until  we 
treat  of  the  life-history  of  each  class. 

13.  In  referring  to  the  Vorticella,  or  bell-shaped  ani- 
malcule, in  our  first  chapter,  mention  was  made  of  its  in- 
crease by  self-division.     The  mass  of  bioplasm  of  which 
it  is  composed  separates  into  two  masses,  which  become 
separate  individuals.     This  mode  of  increase  is  called 
Fission,  and  is  quite  common  among  the  minuter  forms 
of  life.     In  Sarcina  ventriculi,  a  sort  of  vegetable  para- 
site, the  division  is  into  fours,  or  four  times  four. 

14.  A  variety  of  fission,    called   Gemmation,   or  Bud- 
ding, is  often  met  with.     A  portion  projects  from  the 
mass,  and  separates  to  begin   an   individual  existence. 
Thus  in  the  fresh-water  polyp,  or  Hydra,  a  bud  gives 
rise  to  an  organism  like  the  parent,  which  becomes  de- 
tached  and    independent.     Sometimes   the   product  of 
buds  remains  attached,  as  in  plants,  and  in  the  Foram- 


48  THE  SCIENCE  OF  LIFE. 

inifera.  In  other  cases  the  budding  is  internal,  and 
the  progeny  may  or  may  not  remain  attached  to  the 
parent. 

15.  Alternation  of  generations  is  a  term  given  to  ex- 
press a  mode  of  reproduction  in  which  "  the  parent  finds 
no  resemblance  in  his  progeny  until  he  comes  down  to 
his  great-grandson."  The  Jelly-fish,  or  Medusae,  from 
the  huge  masses  cast  up  by  the  waves  of  the  sea-shore, 
to  the  tiny  bell  no  bigger  than  a  pea,  are  developed  in 
this  manner.  A  ciliated  germ,  like  some  of  the  Infusoria 
in  form,  swims  about  awhile,  then  becomes  attached, 
elongates,  and  develops  into  a  polyp  like  the  Hydra. 
The  polyp  becomes  wrinkled  and  subdivides  until  it 

looks  like  a  pile 
of  saucers  with 
scalloped  edges. 
This  breaks  in- 
to segments, 
each  of  which 
becomes  a  jel- 
ly-fish, which 
enlarges  and 
produces  fresh 
germs.  Fig.  5, 

FIG.  5. — Diagram  illustrative  of  the  Development  of  Hydrozoa.  . 

(The  specimen  is  one  of  the  Lucernaridae.) 

i.  Ciliated  embryo  or  "planula."     2.  Hydra  tuba,  showing     production    dlf- 
a  single  individual.     3.  Hydra  tuba  undergoing  segmentation. 

4.  The  segmentation  becoming  more  complete.     5.  More  ad-    iCl'S  ITOm    ITietcl- 
vanced  stage,  in  which  the  tentacles  are  developed  from  the  first  •,         .  i 

or  basal  segment.    6.  Segmentation  complete,  giving  rise  to  a     HlOrpnOSlS,  SUCn 
free  swimming  Medusoid.  as      a      butterfly 

undergoes  in  passing  from  the  egg  to  the  perfect  insect, 
or  as  most  animals  pass  through  in  the  embryonic  state. 


PARENTAGE.  49 

The  caterpillar  becomes  a  butterfly,  but  the  hydra-like 
individual  referred  to  produces  a  number  of  Medusae. 

1 6.  Partheno-genesi$\  or  virgin  production,  denotes  the 
production  of  new  individuals  by  virgin  females  without 
the  intervention  of  a  male. 

The  Aphides,  or  plant  lice,  so  often  found  parasitic 
on  plants  at  the  close  of  autumn,  consist  of  winged  males 
and  wingless  females.  The  ova,  or  eggs,  are  dormant 
through  the  winter,  and  the  young  hatched  in  the  spring 
are  sexless,  but  produce  viviparously  a  brood  like  them- 
selves, and  this  generation  produces  another,  and  so  on 
for  ten  or  twelve  generations,  the  last  brood  being  male 
and  female  as  at  first.  Many  other  tribes  of  insects  af- 
ford examples  of  partheno-genesis. 

17.  The  subject  of  this  chapter  brings  us  to  some  of 
the  deepest  mysteries  of  creation.     The  parentage  of  all 
living,  and  the  various  modes  in  which  the  principle  of 
parentage  is  manifested — such  topics  are  wonderful  seed- 
thoughts.     It  is  not  likely  that  we  shall  ever  understand 
fully  the  repetition  of  individuality,  but  we  see  enough 
to  indicate  some  of  the  plans  of  the  Designer  of  all. 
"  Lo !  these  are  parts  of  his  ways  .  .  .  but  the  thunder 
of  his  power  who  can  understand?" 

Some  analogies  between  the  teachings  of  biology  as 
to  the  genesis  of  living  things,  and  some  of  the  state- 
ments of  Scripture,  may  be  readily  traced.  Mr.  Joseph 
Cook  has  been  sharply  criticised  for  comparing  the  birth 
of  Jesus,  as  revealed  in  the  Gospels,  with  partheno-gen- 
esis ;  yet  he  had  reason  for  so  doing,  nor  is  he  alone  in  his 
opinion.  In  President  Dawson's  "  Origin  of  the  World" 
we  read,  "  It  is  curious  that  the  Bible  suggests  three 


50  THE  SCIENCE  OF  LIFE. 

methods  in  which  new  organisms  may  be,  and,  according 
to  it,  have  been,  introduced  by  the  Creator.  The  first  is 
that  of  immediate  and  direct  creation,  as  when  God  cre- 
ated the  great  Tanninim,  (whales.)  The  second  is  that 
of  mediate  creation,  through  the  materials  previously 
existing,  as  when  he  said,  '  Let  the  land  bring  forth 
plants,'  or  '  Let  the  waters  bring  forth  animals.'  The 
third  is  that  of  production  from  a  previous  organism  by 
power  other  than  that  of  ordinary  reproduction,  as  in 
the  origination  of  Eve  from  Adam,  and  the  miraculous 
conception  of  Jesus." — P.  229. 

t4  The  Bible  indicates  some  ways  in  which  living  creat- 
ures may  be  modified,  or  changed  into  new  species,  or 
may  give  rise  to  new  forms  of  life.  The  human  body  is, 
we  are  told,  capable  of  transformation  into  a  new  or  spir- 
itual body,  different  in  many  important  respects,  and  the 
future  general  prevalence  of  this  change  is  an  article  of 
religious  faith.  The  Bible  represents  the  woman  as  pro- 
duced from  the  man  by  a  species  of  fission,  not  known 
to  us  as  a  natural  possibility,  except  in  some  of  the  lower 
forms  of  life.  The  birth  of  the  Saviour  is  represented  as 
having  been  by  partheno-genesis,  and  if  it  had  pleased 
God  that  Jesus  was  to  remain  on  earth  as  the  progenitor 
of  a  new  and  higher  type  of  man  to  replace  that  now  ex- 
isting, this  might  be  regarded  as  the  introduction  of  a 
new  species." — P.  378. 

It  certainly  disarms  skepticism  and  strengthens  the 
probability  of  Bible  history,  to  find  such  analogies  be- 
tween the  natural  world  and  the  record  of  revelation. 

Living  beings  are  not  fortuitous  nor  necessary  group- 
ings of  atoms,  either  mechanical,  as  Monism  teaches,  01 


PARENTAGE.  5 l 

monads  of  force,  as  Leibnitz  wrote,  but  sparks  of  spir- 
itual existence,  given  off  voluntarily  from  the  Eternal 
Parent,  having  various  powers  and  capacities,  yet  each 
capable  of  pressing  the  fleeting  atoms  of  matter  into  its 
service  during  the  period  alloted  to  it  in  the  world.  Of 
all  living  beings  man  is  nearest  like  the  Great  Father, 
in  whose  image  we  were  created,  and  who,  when  heart 
and  flesh— body  and  animal  life — shall  fail,  may  be  the 
strength  of  our  hearts  and  our  portion  forever. 
"  For  we  also  are  his  offspring." 


52  THE  SCIENCE  OF  LIFE. 


CHAPTER  IV. 
TISSUE    FORMATION. 

In  regard  to  the  physical  universe,  it  might  be  better  tc  substitute  for 
the  phrase  "  government  by  laws,"  "  government  according  to  laws,"  mean- 
ing thereby  the  direct  exertion  of  the  Divine  Will,  or  operation  of  the  First 
Cause  in  the  Forces  of  Nature,  according  to  certain  uniformities  which 
are  simply  unchangeable,  because,  having  been  originally  the  expression  of 
Infinite  Wisdom,  any  change  would  be  for  the  worse.— DR.  W.  B.  CAR- 
PENTER. 

1.  A  TISSUE  is  a  structure  which  presents  a  special 
form  and  serves  a   special  purpose.      Thus  we  find  in 
plants  cellular  and  woody  tissues,  and  in  animals  muscu- 
lar,   nervous,    connective,    and    epithelial    tissues,    etc. 
From  tissues  are  formed  organs,  as  the  circulatory,  res- 
piratory, or  digestive  organs.      A  collection  of  organs 
serving  a  common  purpose  is  called  a  system,  as  the  nu- 
tritive, generative,  or  nervous  systems.     The  union  of 
systems  in  a  co-ordinate  organism,  or  the  equivalent  of 
such  a  union,  forms  an  individual.     An  individual  among 
the  higher  forms  of  life  is  a  very  complex  arrangement 
of  systems  and  organs  ;  but  in  the  lower  forms  more 
simple  arrangements  prevail,  which  may  be  considered 
equivalent,  or  representative,  of  complicated  organs,  as 
in  the  Rhizopods,  referred  to  in  Chap.  II.,  Sec.  5. 

2.  In  the  formation  of  tissues,  the  peculiar  living  prop- 
erties of  bioplasm  already  described  ;  the  physical  agen- 
cies of  light,  heat,  electricity,  and  moisture  ;  chemical 
reactions  such  as  are  common  to  inanimate  substances  ; 


TISSUE  FORMATION.  53 

and  certain  properties  called  osmose  and  molecular  coales- 
cence, all  combine,  so  as  to  render  the  study  of  some 
tissues  quite  complex.  In  other  cases  the  mode  of  for- 
mation is  readily  traced. 

3.  The  action  of  physical  stimuli,  as  heat,  etc.,  upon 
bioplasm  itself  is  yet  very  imperfectly  known.  Light  is 
not  essential  to  its  development,  as  is  seen  in  the  growth 
of  fungi,  the  cells  of  the  interior  of  organisms,  and  of  the 
embryo  in  the  dark.  Many  experiments  on  bioplasm 
have  shown  that  a  moderate  increase  of  temperature 
quickens  its  movements,  and  a  corresponding  depression 
retards  them.  Electrical,  mechanical,  and  chemical  stim- 
ulation have  similar  effects  to  heat.  Yet  the  action  of 
these  stimuli  vary  in  different  cases.  The  motions  of 
amoebae  are  arrested  by  iced  water,  and  recommence  on 
raising  the  temperature,  yet  the  segmentation  of  trouts' 
eggs  proceeds  well  in  iced  water,  but  in  a  warm  room  they 
soon  die.*  If  the  change  of  intensity  in  the  stimulation 
be  made  gradually,  and  not  suddenly,  the  living  matter 
will  sometimes  adapt  itself  to  it  without  serious  disturb- 
ance. Animals  have  been  frozen  and  revived,  and  there 
are  instances  on  record  of  men  enduring  for  a  consider- 
able time  without  much  inconvenience  the  heat  of  ovens 
raised  to  500°  F. 

The  influence  of  light,  heat,  and  electricity  upon  formed 
material  of  different  kinds  is  very  great,  but  the  com- 
plexity of  the  organism  and  of  the  phenomena  render  it 
difficult  to  know  what  part  is  supplied  by  the  bioplasm 
and  what  by  its  product.  The  vegetable  bioplasm  of 
the  interior  grows  and  reproduces  its  kind,  but  the 

*  Strieker's  "  Manual  of  Histology." 


54  THE  SCIENCE  OF  LIFE. 

green  chlorophyll  which  it  forms  beneath  the  epidermis, 
especially  in  the  leaves,  under  the  influence  of  light  alone 
breaks  up  carbonic  acid  for  the  supply  of  carbonaceous 
food.  The  influence  of  the  more  luminous  rays,  as  the 
yellow  and  orange,  is  greater  in  this  respect  than  the 
others.  Gardeners  blanch  certain  plants  by  raising  them 
in  the  dark,  yet  in  the  first  part  of  the  germination  of 
seeds  Light  is  injurious  rather  than  beneficial.  The  in- 
fluence of  Light  upon  the  direction  of  the  growing  parts 
of  plants,  the  opening  and  closing  of  flowers,  etc.,  may 
be  chiefly  owing  to  its  influence  upon  the  chlorophyll 
referred  to  above,  or  it  may  be  in  some  degree  a  direct 
mechanical  stimulus.  The  same  amount  of  Light,  how- 
ever, is  not  required  for  all  plants.  Some  require  a  very 
different  amount  than  others.  Among  animals  Light  has 
considerable  influence  upon  colors,  and  still  more  upon 
the  process  of  development.  Persons  who  live  in  cellars 
or  in  dark  streets  are  apt  to  produce  deformed  children, 
while  recoveries  from  disease  are  promoted  by  the  access 
delight. 

To  every  species  of  plant  and  animal  there  is  a  conge- 
nial and  favorable  temperature,  although  great  varieties 
exist  in  this  respect,  as  well  as  in  the  power  of  adapta- 
tion to  extreme  conditions.  Many  plants,  for  example, 
perish  with  the  slightest  frost,  yet  the  little  fungus 
(Torula)  which  is  the  principal  agent  in  yeast,  does  not 
lose  its  vitality  at  76°  below  zero,  although  requiring  a 
somewhat  elevated  temperature  for  its  active  growth. 

Electricity  possesses  the  power  of  exciting  the  con- 
tractility of  tjie  muscular  fibers  and  the  nervous  force 
in  animals  in  a  remarkable  degree.  It  has,  however. 


TISSUE  FORMATION.  55 

mechanical,  chemical,  and  thermal  influence,  in  addition 
to  its  own  special  power,  so  as  to  be  a  very  valuable 
agent  in  scientific  medicine ;  yet  the  nature  of  its  rela- 
tion to  the  living  organism  is  not  yet  understood. 

In  every  organized  being  there  is  an  incessant  play 
of  most  varied  actions.  Buffon  well  said,  "  The  animal 
combines  all  the  forces  of  nature ;  his  individuality 
is  a  center  to  which  every  thing  is  referred,  a  point 
reflecting  the  whole  universe,  a  world  in  miniature."  It 
is  a  one-sided  philosophy,  however,  which 
sees  in  the  living  thing  nothing  more  than 
the  forces  which  are  outside  of  it  and  play 
upon  it,  and  are,  to  a  great  degree,  subject 
to  it. 

4.  Osmose,  or  osmotic  action,  is  a  property 
of  animal  and  vegetable  membrane,  and  of 
some  other  porous  or  soft  materials,  by  which 
liquid  substances  may  be  separated  from 
each  other.  If  two  liquids  (or  gases)  capable 
of  mixing  with  each  other  are  separated  by 
paper,  caoutchouc,  or  a  bladder,  one  liquid 
being  suspended  in  a  bladder,  or  in  a  cylinder 

..i      .,       ,  .       .     ,  FIG.  6.— Blad- 

with  its  lower  end  tied  over  with  bladder,  der  containing 
etc.,  and  immersed  in  the  other  liquid,  the  ^ruap'  tua^ac^ 
liquid  within  will  pass  through  the  bladder  p^ged  in  a  ves- 

.   ^  sel  of  water.  The 

into  the  other,  (exosmose^)  or  the  liquid  with-  inward  motion  of 

•11  •  11111  /         T  \  l^e  water  (endos- 

out  will  pass  into  the  bladder,  (endosmose^  or  mose)  exceeds  the 
both  endosmose  and  exosmose  will  take  ^Tof  the  Tyr-" 
place  at  the  same  time  until  there  is  an  equal  up'  (exosmose') 

»  and    presses    the 

proportion  of  liquids  on  either  side.  (Fig.  6.)  fluid  UP  the  tube- 
These  phenomena  are  owing  to  the  physical  attraction 


56-  THE  SCIENCE  OF  LIFE. 

the  two  liquids  have  for  each  other  and  for  the  mem- 
brane separating  them. 

Crystallizable  bodies,  as  salt,  niter,  etc.,  when  in  solu- 
tion, and  substances  allied  to  them,  as  hydrochloric  acid, 
and  alcohol,  pass  readily  through  membrane ;  but  bodies 
which  do  not  crystallize,  but  assume  the  gelatinous  form, 
as  gum,  starch,  albumen,  hydrate  of  alumina,  etc.,  pass 
through,  if  at  all,  with  great  slowness.  Such  bodies  are 
called  colloid,  or  glue-like.  Osmose  occurs  through  all 
jelly-like  bodies,  as  bioplasm,  as  well  as  through  fully 
formed  membrane,  and  in  this  manner  various  liquids 
are  absorbed  or  imbibed  by  the  tissues. 

5.  Molecular  coalescence  is  a  term  applied  to  the  modi- 
fication of  ordinary  forms  of  inorganic  particles  which 
occurs  when  they  combine  in  the  presence  of  organic 
matter.  Thus  it  has  been  found  that  the  crystallization 
of  certain  salts  of  lime,  as  the  carbonate,  when  occurring 
in  a  solution  of  some  organic  colloid,  as  gum-arabic,  al- 
bumen of  eggs,  blood-serum,  and  gelatine,  is  so  modified 
by  such  a  solution  as  to  resemble  many  of  the  calcareous 
deposits  found  in  nature. 

The  bottom  of  the  middle  and  northern  parts  of  the 
Atlantic  Ocean  is  found  by  the  deep-sea  dredge,  even 
at  the  depth  of  nearly  three  miles,  to  be  covered  with  a 
sort  of  slimy  ooze,  which  Prof.  Huxley  formerly  deemed 
to  be  of  animal  nature,  and  termed  Bathybius.  More 
recent  investigations  have  led  him  to  change  this  opin- 
ion. It  is  regarded  as  a  gelatinous  inorganic  secretion, 
or  a  product  of  Diatoms,  a  family  of  minute  Algae.  In 
this  slime  great  numbers  of  globular,  shell-like  micro- 
scopic masses  are  found,  similar  to  those  in  the  chalk 


TISSUE  FORMATION.  57 

strata  of  the  earth's  crust.  By  experiments  in  molec- 
ular coalescence  similar  forms  have  been  produced  arti- 
ficially. 

Spicules,  like  those  in  the  skin  of  certain  marine  ani- 
mals, have  also  been  formed  by  molecular  coalescence, 
as  well  as  laminated  plates  like  cuttle-fish  bone.  It  is 
quite  probable  that  many  calcareous  deposits  in  tissues, 
as  in  the  shell  of  the  bird's  egg,  in  the  scales  of  fishes, 
as  well  as  in  bone  and  teeth,  may  be  thus  accounted  for. 
The  presence  and  contact  of  living  colloid  matter  modi- 
fies the  ordinary  laws  of  crystallization,  and  produces 
forms  differing  according  to  the  endowment  of  the  bio- 
plasm. 

6.  In  vegetables  most  of  the  organs  are  composed  of 
cellular  tissue,  or  a  congeries  of  cells.    The  surface  of  the 
cell,    which    originates    by    fission     from    bioplasm,    is 
changed    into   membrane^    or 

cell-wall,  while  a  nucleus,  (one 
or  more,)  now  generally  re- 
garded as  a  concentration  of 
vital  power,  appears  inside. 
Within  the  nucleus,  another 
spot,  the  nucleolus,  is  some- 
times seen.  (Fig.  7.)  The 
cell  itself  presents  the  ap- 

FIG.    7. — Vegetable  cell,  with   nucleus 

pearance  of  a  bladder  full  of  and  nucieoius. 

fluid  or  semi-fluid  material,  in  the  midst  of  which  the 

nucleus  is  visible. 

7.  Many  simple  vegetable  forms  consist  of  a  single 
cell,  the  membranous  wall  of  which  is  a  species  of  formed 
material  called  cellulose,  a  substance  analogous  to  starch. 


5  8  THE  SCIENCE  OF  LIFE. 

Within  this  membrane  the  bioplasm  is,  as  it  were,  im- 
prisoned, yet  receiving  pabulum  by  endosmose,  or 
through  pores  left  in  the  membrane,  its  vital  functions 
remain.  In  the  higher  plants,  as  the  palm  or  the  oak, 
the  structure  is  but  an  aggregation  of  cells,  some  of 
which  have  been  modified  in  form  to  serve  special  uses. 

8.  Near  the  vegetable  cell-wall  the  bioplasm  appears 
less  fluid  than  in  the  middle  of  the  cell,  and  certain  chem- 
ical agents  cause  a  partial  separation  from  the  membrane, 
so  as  to  present,  under  the  microscope,  the  appearance  of 
a  secondary  and  gelatinous  membrane — the  primordial 
utricle. 

In  some  vegetable  cells  the  molecular  movement  of 
the  contained  bioplasm  is  quite  evident,  and  has  re- 
ceived the  name  of  Cyclosis.  It  may  be  seen  under  the 


FIG.  8. — Three  cells  from  the  hair  of  a  potato,  showing  Cyclosis.     Bioplasmic  threads 
proceed  from  the  nuclei,  along  which  the  current  flows,  in  the  direction  of  the  arrows. 

microscope  in  the  stinging  hair  of  the  nettle,  and  in 
hairs  from  the  calyx  of  Tradescantia  Virginica,  etc. 
(Fig.  8.) 

9.  Within  the  cell-wall  the  bioplasm  may  be  trans- 
formed into  chlorophyll,  or  green  coloring  matter,  into 
starch,  gum,  oil,  resin,  sugar,  or  other  kind  of  formed 
material  or  mineral  substances  may  crystallize  in  the 
cells,  forming  what  are  known  as  raphides.  The  variety 


TISSUE  FORMATION. 


59 


of  vegetable  products  of  this  kind  is  very  great.     (Figs. 
9  and  10.) 


FIG.  9.— Cellular  tissue  of  Cc- 
reus  variabilis,  containing :  a.  a. 
Jelly,  b.  Crystals,  c.  Starch- 
granules. 


e  / 

FIG.  10. — a.  b.  Cells  of  a  potato,  containing 
starch,  c.  Starch-grains  apart,  d.  e.f.  Wheat- 
starch  in  different  positions. 


10.  There  is  often  a  deposit  of  silica  on  the  cell-wall, 
as  in  grasses,  horsetails,  and  diatoms.      Some  of  these 
latter  are  beautifully  marked  with  lines  and  dots,  rival- 
ing the  most  complicate  patterns  of  engine-turned  en- 
graving. 

11.  Cell-membrane,  as  all  other  kinds  of  formed  mate- 
rial, grows  by  addition  inside,  so  that  the  inner  layer  is 
the  youngest.     The  formed  material  may  get  so  thick 
that   nutrition  ceases  and  the  bioplasm  is  wholly  trans- 
formed, or  dies.     The  solid  deposit  which  fills  up  the 
cells  of  woody  fiber  is    known   as  sclerogen,  or  woody 
tissue.    (Fig.    u.)      In   Coniferous   plants  the  fibers  are 


FIG.  n. — \Voody  fiber. 


6o 


THE  SCIENCE  OF  LIFE. 


marked  with  depressions,  or  concave  spaces,  (glands?) 
the  centers  of  which  are  penetrated,  as  if  some  sort  of 
special  communication  existed  between  the  bioplasm 


FIG.  12. — Glandular  fiber,    a.  External  appenr.-uire.    b.  The  sides  of  two  tubes,  or  fibers, 
in  contact,    c.  d.  Lenticular  cavity  between  the  lubes. 

of  contiguous  cells.    (Fig.  12.)     Sometimes  sclerogen  is 
deposited  within   the  cell-wall  in   such  a  manner  as  to 

produce  dots,  or  pores,  or  rings, 
or  spiral  fibers,  which  give 
names  to  the  several  kinds  of 

FIG.  13.— Annular  and  dotted  cells.       Cells.     (Fig.    13.) 

12.  Vegetable  cells  are  of  various  shapes,  according  to 
the  purposes  they  subserve.  They  may  be  conical,  oval, 
prismatic,  cylindrical,  sinuous,  branched,  entangled,  or 
stellate.  (Fig.  14.)  Tubes,  or  vessels,  are  formed  of 
elongated  cells.  Sometimes  such  cells  join  end  to  end, 
and  the  partition  being  removed  by  absorption,  a  long 
tube  is  formed.  Such  vessels  may  be  dotted,  reticu- 
lated, annular,  or  spiral,  from  the  deposit  of  woody 
tissue,  or  sclerogen.  (Fig.  15.)  In  the  stem  of  Endog- 
enous plants,  as  palms,  etc.,  bundles  of  fibre-vascular 


TISSUE  FORMATION. 


61 


FIG.    14. — Various   forms  of  cells  :    a.  Conical,     b.  Oval.     c.  Prismatic,     d.  Cylindric. 
•-_„•  Sinuous,    f.  Branched,    g.  Entangled,    h.  Stellate,     z.  Fibro-cellular  tissue. 


FlG.  15.— Annular,  dotted,  and  spiral  vessels  and  ducts. 

tissue  occur  among  a  mass  of  cellular  tissue;    but  in 
Exogens,  as  the  maple,  oak,  etc.,  we'  find  a  more  reg- 
ular arrangement  of  pith,  medullary  sheath,  wood,  bark, 
6 


62 


THE  SCIENCE  OF  LIFE. 


FIG.  16.— a.  Transverse  stem  of  Endogen,  (Palm.)   b.  Of  Exogen,  (Buckthorn.)   c.  Trans- 
verse and  longitudinal  section  of  Maple  in  the  beginning  of  the  second  year 

and  medullary  rays.  (Fig.  16.)  The  pith  is  the  cellular 
tissue  of  the  center ;  the  medullary  sheath  a  ring  of 
spiral  vessels  round  the  pith,  which  sends  projections 
through  it  to  form  the  medullary  rays ;  the  wood  con- 
sists of  concentric  layers  of  woody  and  vascular  tis- 
sue ;  and  the  bark  is  trade  of  cellular  materials,  some- 
times containing  branching  vessels  (laticiferous  tissue) 
conveying  milky  juice. 


TISSUE  FORMATION. 


13.    Leaf -tissue   is  made  up  of  cells,  with   cavities, 
fibre-vascular  bundles,  and  epidermis.    (Fig.   17.)      The 


FIG.  17. — Perpendicular  section  of  Melon-leaf:   h.  hairs;  st.  stomata ;  fv.  fibro-vas- 
cular tissue  of  the  veins. 


latter  is  a  sort  of  skin  composed  of  compressed  cells, 
among  which  are  found  openings,  or   pores,   (stomata^] 

each  guarded  by  two  or 
more  elastic  cells  which 
regulate  evaporation  and 
respiration  by  their  ex- 
pansion. (Fig.  1 8.) 

From  the  surface  of 
the  epidermis  arise  hairs, 
formed  of  minute  expan- 
sions of  cellular  tissue. 
They  are  of  various  forms. 

FIG.  18.— Epidermis  of  Madder,  with  stomata.       Some      of     them      SCCretC 

volatile  oil,  others,  as  the  nettle,  an  acrid  fluid.     They 


64  THE  SCIENCE  OF  LIFE. 

often   form  microscopic   objects  of  great  beauty.  (Fig. 


FIG.  19. — Various  forms  of  vegetable  hairs. 

The  poet  Goethe  first  clearly  showed  that  the  various 
parts  of  the  plant,  from  the  seed  to  the  blossom,  are  but 
modifications  of  the  leaf.  All  the  parts  of  a  flower, 
calyx,  corolla,  stamens,  and  pistil,  are  only  leaves  adapt- 
ed for  'peculiar  functions.  They  were  not  originally 
leaves,  and  afterward  transformed,  but  they  are  formed 
of  the  same  elements,  and  arranged  upon  the  same  plan, 
and  in  the  changes  which  they  undergo  and  the  relation 
they  bear  to  each  other,  they  follow  the  same  laws  as 
leaves  do. 

.  All  leaves  are  arranged  upon  the  stem  after  two 
leading  patterns — the  whorl  and  the  spiral ;  but  as  by 
teasing  out  the  whorl  we  get  the  spiral,  and  by  com- 
pressing the  spiral  we  get  the  whorl,  we  may  regard 
them  as  essentially  the  same. 

14.    In  the  animal   kingdom,  with  the  exception  of 


TISSUE  FORMATION.  65 

those  simple  forms  of  life  already  described,  which  in- 
crease by  fission  or  budding,  (Chap.  III.,  Sec.  12,  13,)  the 
germ  of  all  the  tissues  is  first  a  piece  of  simple  bioplasm 
derived  from  the  vesicles  of  the  ovary.  This  is  fertilized 
by  fusion  with  similar  bioplasm  derived  from  the  male. 
It  then  acquires  a  membrane,  and  exhibits  a  nucleus 
and  nucleolus,  as  in  the  case  of  the  primitive  vegetable 
cell.  Changes,  however,  take  place  in  the  animal  ovum 
which  we  do  not  observe  in  the  vegetable,  and  these 
changes  differ  also  in  the  different  classes  of  animals. 
In  the  higher  classes  the  ovum  separates  into  two 
spheres,  which  sub-divide  into  four,  then  into  a  mul- 
berry-like mass  of  cells,  or  morula.  (Fig.  20.)  These  cells 


FIG.   20. — Segmentation  of   Mammalian  Egg.     A.   Division  into  halves.     B.    Further 
subdivision.     C.  Mulberry  mass,  or  Morula. 

in  the  vertebrates  arrange  themselves  into  a  layer  lining 
the  vitelline  membrane,  on  one  side  of  which  is  a  sort  of 
pouch,  or  blastoderm,  consisting  of  three  layers  of  cells, 
the  epiblast,  the  mesoblast,  and  the  hypoblast.  The 
first  of  these  produces  the  skin,  the  middle  one  the 
nervous,  muscular,  and  vascular  systems,  and  the  latter 
the  lining  of  the  intestinal  and  respiratory  organs. 

The  alimentary  canal  is  at  first  a  straight  tube  closed 

at  both  ends.     As  it  grows  faster  than  the  body  it  is 
6* 


66  THE  SCIENCE  OF  LIFE. 

thrown  into  a  spiral  coil,  and  at  several  points  it  dilates, 
to  form  the  stomach,  etc.  The  mouth  is  developed 
from  an  infolding  of  'skin.  The  liver  is  an  outgrowth 
from  the  digestive  tube,  at  first  a  cluster  of  cells,  then  oi 
follicles,  and  finally  a  true  gland.  The  lungs  first  ap- 
pear as  minute  buds  from  the  upper  part  of  the  aliment- 
ary canal,  or  pharynx. 

15.  The  transformation  of  the  cells  of  the  blastoderm 
into  various  animal  tissues  is  effected  in  various  ways. 

a.  An  interstitial  deposit  of  formed  material  may  occur 
in  the  bioplasm,  or  cell.     Thus  oil-globules,  pigment,  or 
vacuities  may  greatly  modify  the  appearance  and  actions 
of  the  cell.     The  action  of  tannin,  or  boracic  acid,  etc., 
upon  the  red  blood  disks  of  animals,  shows  each  of  them 
to  be  really  double,  having  a  continuous  interstitial  sub- 
stance deposited  in  each  disk.     Prof.  Brucke,  who  first 
investigated  this  structure,  called  the  parts  of  the  disk 
respectively,  the  zooid  and  the  cecoid,  the  former  being 
the  part  which,  in  the  living  state,  contains  also  the 
haemoglobulin,  or  red  coloring  matter. 

b.  Cells  are  sometimes  found   scattered  through  an 
intercellular   material,   the  product  of  cells  or  of  cells 
transformed  and  fused  together.     This  intercellular  mass 
may  either  remain  continuous,  or  split  up  into  fibers. 
In  this  way  fibrous  connective  tissue,  cartilage,  etc.,  may 
be  formed.  (Fig.  21.) 

c.  The  cells  which  cover  surfaces,  and  through  which 
all  interchange  between  the  body  and  the  external  world 
is  carried  on,  are  called  epithelial.     They  differ  in  shape, 
either  from  mutual  pressure   or   function,  some   being 
flat   and    squamous,    (or   scaly,)   and    others   columnar. 


TISSUE  FORMATION.  67 

Some  of  the  latter  have  cilia,  or  hair-like  projections, 
whose    motions    produce    a   current    over   the    surface. 


A 


FIG.  21. — Connective-tissue.     A.  White  and  yellow  fibers.     B.  Developing  Cells  of 
connective  tissue. 

Thus  the  skin,  or  mucous  membrane,  is  not  a  continu- 
ous membrane,  but  made  up  of  cells,  the  nuclei  of  which 
exhibit  the  remains  of  the  bioplasm  or  living  matter 
from  which  they  sprang.  (Fig.  22.) 


FIG.  22. — Epithelial  cells,  i.  Squamous  epithelium  from  the  skin,  showing  the  change 
from  bioplasm  to  horny  scurf.  2.  Tessellated  Ep.  from  serous  membrane.  3.  Columnar 
Ep.  from  intestine.  4.  Ciliated  Ep.  from  air-passages. 


68 


THE  SCIENCE  OF  LIFE. 


d.  In  bone  and  other  hard  tissues,  as  the  teeth,  the 
intercellular  substance  is  solidified  by  salts  of  lime  de- 
posited in  a  modified  form  by  molecular  coalescence. 
Sec.  3.  In  this  case  the  bioplasm,  or  cell,  is  limited  to 
certain  spaces,  or  lacuna,  and  receives  nourishment 
through  small  canals,  or  canaliculi.  (Fig.  23.) 


FIG.   23. — Transverse   section  of  a   long  bone.      a.    Haversian  canal,    b.    Concentric 
laminae,   c.  Laminae  of  connection,    d.  Lacunae,  with  their  system  of  tubes. 


e.  Some  fibrous  structures  may  be  formed  by  moving 
particles  of  bioplasm,  leaving  behind  them  a  thread  of 
formed  material.  In  voluntary  muscular  fiber  this  formed 
material  is  duplex,  and  in  certain  nerve-ganglia  the  fiber 


TISSUE  FORMATION.  69 

is  spirally  coiled  around  another  by  the  forward  and 
rotary  motion  of  the  bioplasmic  cell. 

1 6.  We  may  consider  the  living  organism,  either  ani- 
mal or  vegetable,  as  a  building,  a  workshop,  or  a  labora- 
tory, and  in  each  view  the  cell,  or  bioplasm,  plays  the 
most  important  part. 

If  we  regard  an  organism  as  a  building,  the  cells  are 
the  constituent  parts,  or  building-stones.  The  most 
simple  forms  of  life,  as  we  have  said,  are  single  cells, 
while  the  more  complex  are  composed  of  myriads  of 
these  cells,  with  the  materials  produced  by  them,  ar- 
ranged in  various  forms,  according  to  the  nature  of  the 
individual.  Thus  in  the  yeast-plant  (Torula)  the  cells 
touch  each  other  at  only  one  or  two  points,  while  the 
wood-cells  of  higher  plants  adhere  in  their  entire  extent 
by  means  of  formed  material.  Vessels,  or  ducts,  are 
either  elongated  hollow  cells,  or  are  formed  by  the 
union  of  cells.  In  every  structure,  except  the  most 
primitive,  we  also  find  secret  chambers  and  grottoes 
which  we  should  not  previously  have  suspected  ;  and 
where  strength  is  needed,  provision  is  made  for  it  by  the 
deposit  of  hard  substance,  and  by  the  interlacing  of 
fibers,  once  cellular,  in  a  most  wonderful  manner.  Even 
the  temple  of  Solomon,  in  all  its  glory,  was  not  more 
complete  in  architectural  details  than  the  structure  of 
many  of  our  plants  and  animals.  As  that  temple  was 
said  to  have  been  erected  without  the  sound  of  hammer 
or  saw,  so  the  animated  edifice  is  built  silently,  story 
after  story,  from  day  to  day,  until  its  life-work  is  accom- 
plished. 

Such  a  structure  is  a  workshop,  as  well  as  a  building. 


^o  THE  SCIENCE  OF  LIFE. 

There  is  something  in  it  full  of  peculiar  activity,  alto- 
gether different  from  the  forces  which  belong  to  metals 
and  stones,  or  other  inorganic  bodies.  We  call  it  Life, 
and  the  more  we  observe  its  powers  the  more  we  shall 
be  convinced  that  it  is  the  Master,  and  not  the  slave,  of 
matter,  and  that  the  forming  power  is  different  from  the 
thing  which  is  formed.  It  makes  its  own  workshop  and 
its  own  tools,  and  compels  the  physical  forces  of  inor- 
ganic nature  to  assume  new  and  different  relations,  so  as 
to  serve  its  own  purposes.  It  forms  its  own  building- 
stones,  and  elevates  them  to  their  places  against  gravity, 
removes  such  as  are  in  decay  and  replaces  them  with 
others,  and  strengthens  such  parts  as  are  most  exposed 
to  wear  or  strain. 

The  organism  is  also  a  laboratory.  There  Life,  as  a 
subtle  Alchemist,  sits  and  transmutes  the  chemical  ele- 
ments around  it  into  new  and  useful  forms,  in  a  way 
which  surpasses  all  our  knowledge.  Thus  from  the  same 
materials,  and  under  the  same  conditions  of  light,  heat, 
and  electricity,  one  cell  will  make  starch,  another  fat, 
another  sugar,  albumen,  flesh,  coloring-matter,  acids,  or 
alkalies ;  nay,  even,  in  parts  of  the  same  cell  different 
materials  may  be  produced. 

17.  Every  glance  into  the  marvels  of  organic  structure 
reveals  new  wonders.  As  in  the  remote  regions  of 
space  we  may  trace  myriads  of  suns,  with  nebulous  films 
and  world-islands,  which  hide  from  us  what  is  behind 
them,  so  here  every  step  reveals  something  new  and 
gives  glimpses  of  something  beyond.  The  details  of 
Histology  would  fill  a  large  volume,  and  even  an  ordi- 
nary life-time  is  insufficient  to  do  more  than  to  gather 


TISSUE  FORMATION.  71 

up  a  few  facts  and  arrange  them  in  proper  relations,  yet 
the  pursuit  of  knowledge  continually  brings  us  nearer  to 
the  fountain  of  Absolute  Truth.  To  the  microscope, 
even  more  than  to  the  telescope,  belongs  the  introduc- 
tion of  the  inquirer  into  the  arcana  of  the  universe.  If 
it  does  not  lead  us  outward  into  realms  of  space,  which 
exhibit  the  same  relations  of  scientific  and  abstract  truth 
as  the  world  on  which  we  dwell,  it  leads  us  inward  to- 
ward the  foundations  of  our  own  existence,  and  shows, 
that  the  relations  of  truth  are  as  perfect  in  the  descend- 
ing as  in  the  ascending  sphere.  If  we  see  not  life  itself, 
we  see  its  first  beginnings,  and  the  process  of  its  devel- 
opment. If  we  see  not  Nature  in  her  undress,  we  trace 
the  elementary  warp  and  woof  of  her  mystic  drapery. 
From  both  telescope  and  microscope  alike  we  learn 
that  the  widening  sphere  of  knowledge  is  constantly 
encircled  by  the  unknown/  yet  through  them  we  see 
above  and  beneath  us  a  myriad  instances  of  the  skill  and 
providence  of  a  Great  Designer,  who  is  God  and  Father 
of  all.  The  living  atom  shines  with  truth  no  less  than 
the  star. 

"  Forever  singing  as  they  shine, 
The  hand  that  made  us  is  divine." 


72  THE  SCIENCE  OF  LIFE. 


CHAPTER  V. 

TYPES     OF     CONSTRUCTION. 

.  .  .  Much  less,  then,  have  we  any  idea  of  the  substance  of  God.  We 
know  him  only  by  his  most  wise  and  excellent  contrivances  of  things  and 
final  causes  ;  we  admire  him  for  his  perfections  ;  but  we  reverence  a  ul 
adore  him  on  account  of  his  dominion  :  for  we  adore  him  as  his  servants  ; 
and  a  god  without  dominion,  providence,  and  final  causes,  is  nothing  else 
but  Fate  and  Nature.  Blind  metaphysical  necessity,  which  is  certainly 
the  same  always  and  every-where,  could  produce  no  variety  of  things.  All 
that  diversity  of  natural  things  which  we  find  suited  to  different  times  and 
places  could  arise  from  nothing  but  the  ideas  and  will  of  a  Being  neces- 
sarily existing. — SIR  ISAAC  NEWTON'S  Principia. 

1.  OUR  imperfect  knowledge  of  nature  must  always 
give  a  provisional  character  to   our  classifications.     If 
they  present  the  knowledge  we  possess  in  a  useful  and 
compact  form,  it  is  all  they  can  be  -expected  to  do.     Fur- 
ther knowledge  may  confirm  or  overthrow  the  most  per- 
fectly symmetrical  system.     Tennyson  has  well  sung  : 

"  Our  little  systems  have  their  day, 

They  have  their  day  and  cease  to  be, 
They  are  but  broken  lights  of  thee, 

And  thou,  O  Lord,  art  more  than  they." 
— In  Mcmoriam. 

Yet  an  arrangement  may  be  true  although  imperfect. 
We  may  see  plainly  the  leading  outline,  while  a  myriad 
details  may  be  unknown. 

2.  In  attempting  to  arrange  organic  forms  it  is  impos- 
sible to  place  them  in  a  single  line,  like  the  steps  of  a 
ladder,  according  to  structural  rank.     There  are  no  such 


TYPES  OF  CONSTRUCTION.  73 

gradations  in  nature  as  some  imaginations  have  conceived. 
There  are  so  many  relationships,  both  of  structure  and 
of  function,  that  a  single  series  is  out  of  the  question. 
There  are  many  series,  and  series,  also,  within  series. 
Organic  forms  seem  to  be  placed  in  radiating  groups 
rather  than  lines,  each  group  being  connected,  not  with 
two  groups  merely,  one  above  and  the  other  below,  but 
with  several.  Living  things  are,  therefore,  best  studied 
in  groups,  or  circles,  according  to  prominent  types  or 
representative  forms.  These  groups  will,  doubtless,  be 
unequal  and  dissimilar,  and  will  be  far  from  representing 
the  grade  of  organization  ;  yet  they  will  be  of  great  use, 
not  only  to  the  memory,  but  also  in  indicating  the  gen- 
eral order  of  the  universe. 

3.  The  unity  of  organic  nature  is  seen  in  the  similarity 
of  bioplasm,  or  living  matter  ;  its  variety  is  shown  in  the 
multiform  arrangements  of  structure  in  living  beings. 
That  all  this  variety  can  be  intelligently  connected  to- 
gether in  a  few  comprehensive  groups,  exhibiting  plans 
of  structure,  is  proof  positive  of  the  intelligence  of  the 
creative  power.     Agassiz  has  well  said,  "  If  these  classi- 
fications are  not  mere  inventions,  if  they  are  not  an  at- 
tempt, to  classify  for  our  own  convenience  the  objects  we 
study,  then  they  are  thoughts  which,  whether  we  detect 
them  or  not,  are  expressed  in  Nature — then  Nature  is 
the  work  of  thought,  the  production  of  intelligence,  car- 
ried out  according  to  plan,  therefore  premeditated — and 
in  our  study  of  natural  objects  we  are  approaching  the 
thoughts  of  a  Creator,  reading  his  conceptions,  interpret- 
ing a  system  that  is  his  and  not  ours." 

4.  Types  are  comprehensrve  natural  groups  of  living 


74  THE  SCIENCE  OF  LIFE. 

forms,  founded  on  plans  of  structure  or  structural  ideas. 
Classes  comprise  all  forms  which  agree  simply  in  a  special 
modification  of  the  type  to  which  they  belong.  The 
type  represents  the  plan,  but  there  may  be  several  ways 
of  executing  the  plan,  and  these  ways  illustrate  the 
classes.  In  human  works  of  art  "  there  are  certain  ar- 
chitectonic types,  including  edifices  of  different  materials, 
with  an  infinite  variety  of  architectural  details  and  ex- 
ternal ornaments  ;  but  the  flat  roof  and  the  colonnade 
are  typical  of  all  Grecian  temples,  whether  built  of  mar- 
ble or  granite  or  wood,  whether  Doric  or  Ionic  or  Corin- 
thian, whether  simple  and  massive  or  light  and  orna- 
mental ;  and,  in  like  manner,  the  steep  roof  and  pointed 
arch  are  the  typical  characters  of  all  Gothic  cathedrals, 
whatever  be  the  material  or  the  details.  The  architect- 
ural conception  remains  the  same  in  all  its  essential  ele- 
ments, however  the  more  superficial  features  vary.  Such 
relations  as  these  edifices  bear  to  the  architectural  idea 
that  includes  them  all,  do  classes  bear  to  the  primary  di- 
visions," or  types.*  Thus  Fishes,  Amphibians,  Reptiles, 
Birds,  and  Mammals  are  classes  under  the  Vertebrate 
type  of  animal  life. 

An  Order  is  a  group  of  families,  or  genera,  related 
to  one  another  by  a  common  structure.  Thus  Cats, 
Dogs,  Hyenas,  and  Bears  are  linked  together,  since  their 
teeth,  stomachs,  and  claws  show  the  carnivorous  habits 
of  the  order  Carnivora. 

A  Family,  or  Tribe,  does  not  allude  to  the  progeny  of 
a  known  stock,  but  refers  to  a  group  of  genera  having 
similarity  of  form.  The  term  was  first  introduced  into 

*  Agassiz,  "  Methods  of  Study." 


TYPES  OF  CONSTRUCTION.  75 

Botany  in  France,  in  connection  with  what  is  called  the 
natural  system  of  classification.  To  prevent  confusion, 
the  similarity  of  form  determining  families  should  be 
based  on  structure  and  not  mere  resemblance. 

A  Genus  is  a  group  of  species  having  the  same  essen- 
tial structure.  Thus  the  allied  species,  Cat,  Tiger,  and 
Lion,  belong  to  one  genus. 

A  Species  is  the  smallest  group  of  individuals  which 
can  be  defined  by  several  constant  characteristics.  They 
are  so  alike  that  it  is  possible  for  them  to  have  descended 
from  one  pair.  A  cross  between  two  species,  as  the 
Horse  and  Ass,  is  called  a  hybrid ;  as  the  Mule. 

Individuals  are  the  units  of  organic  life.  A  complete 
animate  existence  is  an  individual,  whether  separate,  as 
man,  or  living  in  a  community,  as  the  Coral.  When  two 
or  more  individuals  differ  by  a  single  peculiarity,  such 
as  color,  or  outline,  or  size,  one  is  called  a  variety  of  the 
other,  as  the  races  of  Men  and  breeds  of  Cattle.  A  cross 
between  distinct  races  is  called  mongrel. 

Vegetables  and  animals  are  separated  from  each  other 
under  the  term  kingdom,  and  the  types  of  structure  in 
each  kingdom  are  called  sub-kingdoms.  Thus  in-the  ani- 
mal kingdom  we  have  the  sub-kingdoms  of  Vertebrates, 
Radiates,  etc. 

There  are  no  such  things  as  genus,  species,  order,  class 
etc.     They  are  but  abstract  terms,  expressing  relation  to 
a  plan,  or  the  harmony  of  intelligent  design  which  pre- 
sides over  all  things. 

5.  A  real  type,  or  plan,  includes  all  those  individuals, 
species,  etc.,  which  are  similar  in  character.  But  it  is 
not  always  easy  to  determine  similarity  of  character. 


76  THE  SCIENCE  OF  LIFE. 

From  the  earliest  times  of  history  down  to  Cuvier, 
naturalists  were  in  the  habit  of  regarding  similarity  of 
external  form  and  evident  purpose  as  indicating  anal- 
ogies, and  so  far  as  functional  design  is  concerned,  the 
principle  may  be  considered  right.  But  purpose  and 
plan  for  a  purpose  are  different,  and  modern  science 
seeks  for  its  types  in  the  characters  of  internal  structure 
and  development. 

6.  Parts,  or  organs,  having  similar  origin  and  develop- 
ment, and  therefore  the  same  essential  structure,  are 
called  homologous ;  while  those  which  are  anatomically 
different,  though  corresponding  in  use,  are  called  analo- 
gous. Thus  in  the  vegetable  kingdom  the  tendril  of  the 
Vine,  which  is  a  transformation  of  the  flower-stalk ;  that 
of  the  Pea,  which  is  a  prolongation  of  the  leaf-stalk  ;  that 
of  Gloriosa,  which  is  the  point  of  the  leaf  itself;  and  that 
of  StrophantkuS)  which  is  the  point  of  the  petal ;  are  all 
analogous,  but  not  homologous.  The  arms  of  Man,  the 
fore-legs  of  a  Horse,  the  paddles  of  a  Whale,  the  wings 
of  a  Bird,  the  front  flippers  of  a  Turtle,  and  the  pectoral 
fins  of  a  Fish,  are  homologous  but  not  analogous.  The 
wings  of  the  Bird,  Flying  Squirrel,  and  Bat  are  not  ho- 
mologous, since  that  of  the  first  is  developed  from  the 
fore-limb  only,  that  of  the  Squirrel  is  an  extension  of  the 
skin  between  the  fore  and  hind  limbs,  and  that  of  the 
Bat  is  a  membrane  between  the  fingers  and  down  the 
side  to  the  tail.  The  air-bladder  of  a  Fish  is  homologous 
with  a  lung,  but  analogous  to  the  air-chamber  of  the 
Nautilus.  In  the  functional  analogies,  perhaps  more 
evidently  than  in  the  structural  homologies,  we  trace 
evidence  of  purpose,  or  design.  "  Blind  metaphysical 


TYPES  OF  CONSTRUCTION.  77 

necessity,"  as  Newton  called  Fate  and  Nature  without 
God,  could  certainly  produce  no  such  "  variety  of  things  " 
as  we  see  here,  while  the  unity  pervading  the  functional 
character  of  the  different  organs  is  plain  enough  proof 
of  their  being  the  work  of  the  same  Artisan. 

Various  functions  are  attained  by  a  modification  of 
similar  structure.  Thus  the  simplest  plant  differs  from 
the  most  complex  principally  in  this — that  the  whole 
external  surface  of  the  former  participates  equally  in  all 
the  operations  which  connect  it  with  the  external  world, 
as  those  of  Absorption,  Exhalation,  and  Respiration, 
while  in  the  latter  these  functions  are  confined  to  certain 
parts  of  the  surface.  So  in  the  highest  animals,  the  or- 
gans adapted  to  the  functions  of  Absorption,  Exhala- 
tion, Respiration,  Secretion,  and  Reproduction,  are  all 
composed  essentially  of  a  membrane  which  is  a  prolonga- 
tion of  the  general  surface,  while  this  general  surface  is 
the  sole  instrument  for  the  performance  of  these  func- 
tions in  the  lowest  animals,  and  shows  no  special  adap- 
tation for  one  or  another  of  them.  So  that  it  may  be 
expressed  as  a  general  truth  of  Biology,  that  "  through- 
out all  animate  Creation,  the  functional  character  of  the 
organs  which  all  possess  in  common,  remains  the  same ; 
while  the  mode  in  which  that  character  is  manifested 
varies  with  the  general  plan  upon  which  the  being  is 
constructed."* 

In  all  living  things  the  attainment  of  function  is  the 
cause  of  modification  of  structure.  This  gives  evidence 
of  Creative  plan,  or  design,  in  direct  opposition  to  the 
theory  of  gradual  evolution  of  structure,  and  is  proof  also 

*  Carpenter's  "General  and  Comparative  Physiology." 

7* 


78  THE  SCIENCE  OF  LIFE. 

of  the  essential  differences  between  living  beings,  since 
the  plan  of  structure  varies  for  attaining  similar  purpose. 
7.  Cuvier  proposed  four  primary  divisions  of  the  ani- 
mal kingdom,  because,  he  said,  they  are  constructed  on 
four  different  plans.  These  plans  may  be  briefly  stated 
as  follows :  "  In  the  Vertebrates  there  is  a  vertebral  col- 
umn terminating  in  a  prominent  head ;  this  column  has 
an  arch  above  and  an  arch  below,  forming  a  double  in- 
ternal cavity.  The  parts  are  symmetrically  arranged  on 
either  side  of  the  longitudinal  axis  of  the  body.  In  the 
MolluskS)  also,  the  parts  are  arranged  according  to  a  bi- 
lateral symmetry  on  either  side  of  the  body,  but  the 
body  has  but  one  cavity,  and  is  a  soft,  concentrated 
mass,  without  a  distinct  individualization  of  parts.  In 
the  Articulates  there  is  but  one  cavity,  and  the  parts  are 
here  again  arranged  on  either  side  of  the  longitudinal 
axis,  but  in  these  animals  the  whole  body  is  divided 
from  end  to  end  in  transverse  rings  or  joints  movable 
upon  each  other.  In  the  Radiates  we  lose  sight  of  the 
bilateral  symmetry  so  prevalent  in  the  other  three,  ex- 
cept as  a  very  subordinate  element  of  structure;  the 
plan  of  this  lowest  type  is  an  organic  sphere,  in  which 
all  parts  bear  definite  relations  to  a  vertical  axis."  * 
Leuckart  proposed  to  subdivide  the  Radiates  into  two 
groups ;  the  Coelenterata,  including  Polyps  and  Acalephs, 
or  Jelly-fishes — and  Echinoderms,  including  Star-fishes, 
Sea-Urchins,  and  Holothurians,  but  Agassiz  shows  that 
the  differences  between  them  are  not  differences  in  the 
plan,  but  merely  a  difference  in  the  execution  of  the 
plan,  since  both  are  equally  radiate  in  structure. 
*  Agassiz,  "  Methods  of  Study." 


NSTRUCTION. 


TYPES  OF  CONSTRUCTION.  79 

By  this  radial  symmetry  we  are  conducted  toward  the 
Vegetable  Kingdom.  Thus  in  the  higher  Fungi  the  dis- 
position of  organs  is  as  radiate  as  in  Radiated  animals. 
In  Mosses  and  Ferns  there  is  a  spiral  arrangement  of 
leaves  around  the  axis,  which  may  be  considered  the 
regular  law  of  growth  in  the  higher  plants,  although 
sometimes  obscured  by  special  modifications. 

8.  It  is  a  popular  error,  fostered  by  the  assertions  of 
certain  Monistic  writers,  that  the  higher  animals  pass 
through  all  the  phases  of  lower  life.  This  false  notion  is 
based  upon  too  strict  an  interpretation  of  Von  Baer's  gen- 
eralization in  Embryology,  that  "  a  heterogeneous  or  spe- 
cial structure  arises  by  gradual  change  out  of  one  more 
homogeneous  or  general."  Every  division  of  the  Animal 
Kingdom  has  its  characteristic  method  of  developing. 
"  The  Vertebrate  arises  from  the  egg  differently  from  the 
Articulate ;  the  Articulate  differently  from  the  Mollusk ; 
the  Mollusk  differently  from  the  Radiate."  *"  Every 
grand  group  early  shows  that  it  has  a  peculiar  type  of 
construction.  Every  egg  is  from  the  first  impressed  with 
the  power  of  developing  in  one  direction  only,  and  never 
does  it  lose  its  fundamental  characters.  The  germ  of  the 
Bee  is  divided  into  segments,  showing  that  it  belongs  to 
the  Articulates ;  the  germ  of  the  Lion  has  the  primitive 
stripe — the  mark  of  the  coming  Vertebrate.  The  blasto- 
dermic  layer  of  the  Vertebrate  egg  rolls  up  into  two 
tubes — one  to  hold  the  viscera,  the  other  to  contain  the 
nervous  cord ;  while  that  of  the  Invertebrate  egg  forms 
only  one  such  tubular  division.  The  features  which 'de- 
termine the  subkingdom  to  which  an  animal  belongs 

,     ,   _    *  Ac-assiz. 


8o  THE  SCIENCE  OF  LIFE. 

are  first  developed,  then  the  characters  revealing  its 
class."  *  Dr.  Carpenter  says  :  "  The  human  embryo  is 
never  comparable  with  a  Fish,  a  Reptile,  or  a  Bird,  much 
less  with  an  Insect  or  a  Mollusk.  However  close  may 
be  the  resemblance  between  the  embryo  of  Man  and  the 
embryo  Fish,  there  is  no  real  correspondence  between 
the  embryo  of  Man  and  the  completed  Fish.  Each  germ 
has  a  certain  capacity  of  development  peculiar  to  itself, 
since  like  produces  like" 

9.  To  attain  a  true  knowledge  of  the  order  of  creation, 
or  of  the  types  of  structure  among  organic  forms,  it  is 
necessary  not  only  to  consider  internal  construction  and 
relationships,  and  the  process  of  embryonic  development, 
but  also  to  trace  the  life-history  of  each,  and  especially 
the  metamorphoses  to  which  they  may  be  subject  at 
various  periods.  Among  the  lower  Fungi  there  is  a 
kind  of  polymorphism  (polys,  many ;  morpha,  form)  fre- 
quent, by  which  several  forms  may  be  developed  by 
spores,  or  seeds,  which  have  identically  the  same  origin. 
Few  animals  come  forth  from  the  egg  in  perfect  condi- 
tion. The  embryonic  Star- fish  has  a  long  body,  with 
six  arms  on  a  side,  from  one  end  of  which  the  young 
Star-fish  is  budded  off.  Soon  the  twelve-armed  body 
dies,  and  the  young  animal  is  of  age.  Most  Insects  un- 
dergo complete  change  of  form,  a  metamorphosis;  i.e.,  ex- 
hibit four  distinct  stages  of  existence — egg,  larva,  pupa, 
and  imago.  Among  the  vertebrates  the  most  common 
and  most  remarkable  transformation  is  that  of  the  Frog. 
It  is  first,  after  hatching  from  the  egg,  a  tadpole,  with  a 
tail,  but  no  legs,  gills  instead  of  lungs,  a  heart  like  that 

*  Orton's  "  Comparative  Zoology." 


TYPES  OF  CONSTRUCTION.  81 

of  a  fish,  a  beak  for  eating  vegetable  food,  and  a  spiral 
intestine  to  digest  it.  As  it  matures,  the  hind  legs  show 
themselves,  then  the  front  pair,  the  beak  falls  off,  the 
tail  and  gills  waste,  lungs  are  formed,  the  digestive  ap- 
paratus is  changed  to  suit  an  animal  diet,  the  heart  is 
altered  to  the  Reptilian  type  by  the  addition  of  another 
auricle — in  fact,  skin,  muscles,  nerves,  bones,  and  blood- 
vessels vanish,  being  absorbed  atom  by  atom,  and  a  new 
set  is  substituted.* 

10.  With  the  caution  referred  to  in  Sec.  I  we  may  pre- 
sent an  outline  of  the  types  of  living  forms. 

The  most  general  and  comprehensive  type  is  that  of 
bioplasm,  or  living  matter,  described  in  Chap.  II,  and 
characteristic  of  both  animals  and  vegetables.  The  next 
most  comprehensive  type  of  structure  is  that  of  Vegeta- 
ble forms  in  which  the  bioplasm  is  invested,  or,  as  it 
were,  imprisoned,  in  each  of  its  component  cells  by  a  sac 
of  cellulose,  or  some  analogous  compound,  (Chap.  IV, 
Sec.  5,)  and  whose  most  characteristic  work,  or  peculiar- 
ity, is  its  power  of  manufacturing  albuminoid  matter  out 
of  simpler  chemical  elements.  In  Animal  forms  there 
is  no  such  cellulose  investment,  nor  can  they  make  albu- 
minoid matter  from  inorganic  elements. 

In  the  Vegetable  Kingdom  we  may  arrange  organic 
forms  under  the  following  general  divisions,  or  principal 
types: 

i.)  PROTOPHYTES,  or  simplest  vegetable  forms,  an- 
swering to  the  Unicellular  Alga. 

2.)  THALLOGENS,  which  are  a  mere  expansion  of  cel- 
lular tissue,  without  complete  distinction  between  stem, 

*  Orton. 


82  THE  SCIENCE  OF  LIFE. 

root,  and  leaves.  These  include  Fungi,  Alga,  and 
Lichens. 

3.)  ACROGENS.  Plants  which  grow  in  height  and  not 
in  diameter.  Liverworts,  Mosses,  and  Ferns. 

4.)  ENDOGENS.  Vascular  plants,  in  which  the  wood 
and  cellular  tissue  are  mixed  throughout,  without  dis- 
tinct annual  layers.  The  seed  has  but  a  single  lobe,  or 
cotyledon. 

5.)  EXOGENS.  Vascular  plants  having  distinct  annual 
layers  of  woody  fibers,  and  radiations  of  tissue  from  the 
medulla  to  the  bark.  The  embryo  has  two  seed-lobes, 
or  cotyledons. 

In  the  Animal  Kingdom  we  have  the  following  typical 
forms,  or  subkingdoms : 

I.  PROTOZOA.     Simplest  animal  forms,  being  com- 
posed of  bioplasmic  jelly.     Monera,  Gregarinay  Rhizo- 
pods,  Infusoria,  and  Sponges. 

II.  RADIATA.     Radiate  animals,  which  are  subdivided 
into— I.  CCELENTERATA,  with  distinct  body-cavity,  ten- 
tacles,  and  nettling  thread-cells.     Hydrozoa,  Anthozoa^ 
Ctenophora.     2.  ECHINODERMATA,  with  distinct  aliment- 
ary canal  and  nervous  ring.     Crinoids,  Asteroids,  Holo- 
thurians,  Echinoids. 

III.  MOLLUSCA.     Soft  unsymmetric  animals.     Digest- 
ive system  developed.    Nervous  system  irregular.    Poly- 
zoans,  Tunicates,  Brachiopods,  Lamellibranckiates,  Gaster- 
opods,  Cephalopods. 

IV.  ARTICULATA.     Nervous    ventral    cord    double. 
Limbs  on  same  side  as  nerve-cords.     Annelids,  Crusta- 
ceans, Arachnoids,  Myriapods,  Insects. 

V.  VERTEBRATA.     Double  nervous  system;   one  on 


TYPES  OF  CONSTRUCTION.  83 

upper  side  of  alimentary  canal,  the  other  spinal ;  limbs 
opposite  nerves.  Fishes,  Amphibians,  Reptiles,  Birds, 
Mammals,  Man. 

II.  In  the  Frontispiece  the  characteristic  features  of 
biological  types  are  represented.  In  the  outline  section 
of  each  of  the  four  types  of  higher  animals  the  large 
shaded  spot  shows  the  alimentary  canal,  the  dark  spot 
the  position  of  the  heart,  and  the  open  rings  the  nervous 
system.  A  diagram  of  the  latter  also  accompanies  each 
of  those  types. 


84  THE  SCIENCE  OF  LIFE. 


CHAPTER  VI. 

PROTOPHYTES. 

Let  no  presuming  impious  railer  tax 
Creative  Wisdom,  as  if  aught  was  formed 
In  vain,  or  not  for  admirable  ends. 
Shall  little  haughty  ignorance  pronounce 
His  works  unwise,  of  which  the  smallest  part 
Exceeds  the  narrow  vision  of  her  mind? 

— THOMSON. 

1.  VEGETABLE  structure  has  been  already  character- 
ized as  bioplasm  imprisoned,  or  invested  with  a  cell-wall 
of  cellulose.     In  some  of  the  simplest  forms,  or  Proto- 
phytes,  each  cell  is  separate  from  the  rest,  others  form 
masses  of  cells  in  a  sort  of  gelatinous  or  slimy  invest- 
ment, while  other  forms  exhibit  a  definite  adhesion  be- 
tween the  cells,  so  as  to  prefigure  a  regular  plant-like 
structure,  although  each  cell  is  a  repetition  of  its  parent- 
cell,  and  is  capable  of  living  apart. 

2.  The  life-history  of  simplest   Protophyte   is   exem- 

plified in  the  Pal-. 
moglcea  macrococ- 
ca,  (Fig.  24;)  a  sort 
of  green  scum  or 
slime,  growing  on 
damp  stones,  etc. 
The  microscope 
shows  this  to  con- 

FIG.  24.— Development  of  Palmoglcea  macrococca.  sist   of  a  multitude 


PROTOPHYTES.  85 

of  green  cells,  each  surrounded  by  a  gelatinous  envel- 
ope, and  sometimes  a  nucleus,  or  more  solid  aggregation, 
which  is  considered  the  center  of  vital  activity,  is  seen 
in  the  cell.  The  green  particles,  or  granules,  which  fill 
the  cells,  are  formed  material  called  chlorophyll.  Through- 
out the  vegetable  kingdom  the  presence  of  chlorophyll 
is  necessary  to  enable  the  plant,  under  the  stimulus  of 
bright  sunlight,  to  break  up  carbonic  acid,  evolve  the 
oxygen,  and  appropriate  carbon  as  food.  In  the  absence 
of  sunlight  all  plants  become  oxidized,  and  evolve  car- 
bonic acid.  The  cells  of  the  Palmogloea  multiply  by 
binary  subdivision,  or  fission.  (Chap.  Ill,  Sec.  12.)  This 
multiplication  is  an  act  of  growth,  and  differs  from  simi- 
lar self-division  in  the  higher  plants  by  the  purpose  man- 
ifested, and  the  plan  for  a  purpose,  seen  in  the  "  differ- 
entiation "  of  cells  in  the  higher  orders  for  the  production 
of  special  organs. 

In  these  lowly  plants  there  is  a  process  similar  to  the 
plan  of  reproduction  in  the  more  complex  forms.  A 
pair  of  cells  will  sometimes  reunite,  or  fuse  together,  first 
by  means  of  a  narrow  bridge,  and  then  a  larger  mass, 
and  finally  a  complete  fusion.  The  mass  is  termed  a 
Spore,  (from  the  Greek  spora,  a  seed,)  and  is  the  primi- 
tive cell  of  a  new  generation  formed  by  fission. 

3.  In  a  form  allied  to  the  above,  the  Protococcus  pluvi- 
alis,  (Fig.  25,)  not  uncommon  in  rain-water,  a  somewhat 
greater  variety  of  conditions  has  been  seen.  It  is  found 
still,  or  quiescent,  and  motile.  In  the  first  form  the  bio- 
plasm is  surrounded  with  a  wall  of  cellulose,  and  filled 
with  granules  of  green  or  red  chlorophyll.  These  still 

cells  multiply  by  self-division,  each  producing  two,  four, 

8 


86  THE  SCIENCE  OF  LIFE. 

eight,  or  sixteen  new  cells.  The  new  cells  are  motile,  hav- 
ing each  two  long  vibratile  filaments  or  cilia.  They  may 

be  seen  swimming, 
tumbling,  or  rotat- 
ing in  the  water. 
At  times  they  are 
surrounded  by  a 
sac,  which  may  be 
at  some  distance 
from  the  bioplasm. 
The  motile  cells 
may  also  multiply 

FIG.  25. — Development  of  Protococcus :  a.  Still  form. 
b.  Motile  form.    c.  Self-division  and  zoospores.  by  Subdivision,  and 

in  some  cases  the  minute  primitive  cells,  when  set  free, 
have  very  active  movements,  and  rank  as  Zoospores,  (liv- 
ing spores,)  or  Micro-gonidia,  (small  angular  particles, 
from  division  of  the  bioplasm.)  The  varieties  connected 
with  the  history  of  this  single  plant  have  been  sometimes 
described  as  distinct  species,  and  even  genera  of  Animal- 
cules, because  of  their  shape  and  motions. 

4.  The  family  of  Palmellacece,  to  which  the  forms  re- 
ferred to  belong,  contain  some  kinds  of  singular  interest. 
The  "  Red  Snow,"  which  sometimes  colors  extensive 
Alpine  or  Arctic  tracts,  is  composed  of  myriads  of  Pro- 
tococcus cells,  in  a  quiescent  state,  with  the  chlorophyll 
of  a  red  color.  The  Palmella  cruenta,  or  "  Gory  Dew," 
appears  sometimes  as  tough  gelatinous  masses  of  the 
color  of  coagulated  blood,  and  extends  over  a  consider- 
able area.  In  this  way  we  may  account  for  showers  of 
flesh,  blood,  etc.,  which  are  often  regarded  as  bad  omens 
by  the  ignorant. 


PROTOPHYTES.  8? 

5.  The  family  Volvocinea  has  been  long  considered 
of  singular  beauty  and  interest  to  the  microscopist. 
The  Volvox  globator  (Fig.  26)  was  described  by  Leeu- 
wenhoek  about 
one  hundred  and 
fifty  years  ago, 
and  from  its  shape 
and  rolling  mo- 
tion was  called  the 
globe  animalcule, 
but  its  vegetable 
character  is  now 
generally  admit- 
ted. It  is  about 

One      thirtieth      of  FIG.  26.-Volvox  globator. 

an  inch  in  diameter,  and  appears  to  the  unassisted  eye 
to  be  a  little  green  speck  moving  slowly  through  the 
water.  On  examining  with  the  microscope  the  Volvox 
is  seen  to  be  a  pellucid  sphere  studded  with  minute 
green  spots,  connected  together  by  threads.  From  each 
of  these  spots  proceed  two  cilia,  so  that  the  entire  sur- 
face of  the  globe  is  beset  with  vibratile  filaments,  to  whose 
combined  action  its  rolling  motion  is  due.  Within  the 
globe  may  be  generally  seen  from  six  to  twenty  other 
globes,  of  varying  sizes,  which  are  set  free  by  the  burst- 
ing of  the  parent  globe.  Sometimes  a  third  generation 
may  be  seen  within  the  secondary  spheres.  Careful  ob- 
servation of  the  development  of  the  Volvox  has  shown 
that  the  ciliated  cells  referred  to  above,  analogous  to  the 
zoospores  of  Protococcus,  sometimes  appear  like  moving 
Amoebae.  (Chap.  II,  Sec.  2.)  This  is  not  an  uncommon 


88 


THE  SCIENCE  OF  LIFE. 


phenomenon  among  Protophytes,  and  shows  that  the 
bioplasm  of  the  vegetable  and  animal  cell  have  similar 
properties. 

6.  Dr.  Carpenter  recommends  those  who  wish  to  study 
the  development  of  "  zoospores,"  and  other  phenomena 
of  Protophytes,  to  have  recourse  to  the  little  plant  called 
Achyla  prolifcra,  which  grows  parasitically  upon  the 

bodies  of  dead  flies 
in  water,  etc.  The 
naked  eye  perceives  it 
as  tufts  of  minute  col- 
orless filaments, which 
the  microscope  shows 
to  be  long  tubes  con- 
taining granular  bio- 
plasm, which  exhib- 
its the  motion  called 
Cyclosis.  (Chap.  IV, 
Sec.  6.)  After  about 
thirty-six  hours  the 
bioplasm  accumulates 
in  the  dilated  ends  of 
the  filaments,  and  its 

FlG.  27. — Development  of  Achyla  prolifera  :  A.  Di- 
lated extremity  of  a  filament,  6,  separated  from  the  endochrome,   Or  gran- 
rest  by  a  partition,  «,  and  containing  young  cells  in  t                  I'm     f  f  **r 
progress   of  formation.      B.   Conceptacle    discharging  Ulai>     COJ                       natter, 
itself,  and  setting  free  young  cells,  a,  3,  c.    C.  Portion  Breaks      UP      into      dis- 
of  filament,  showing  the  course  of  the  circulation  of 
granular  protoplasm.  tinct     ttiaSSCS,    each    of 

which  becomes  a  zoospore,  or  "  motile  gonidium,"«with 
cilia,  and  is  set  free  by  rupture  of  the  wall  of  the  parent 
cell.  (Fig.  27.) 

7.  The  family  Desmidiacece  consists  of  minute  Proto- 


PROTOPHYTES. 


89 


phytes  of  a  grass-green  color,  growing  in  fresh  water. 
The  cells  are  generally  independent,  but  in  some  species 
remain  adherent  one  to  another  so  as  to  form  a  filament. 


FIG.  28.—  Various  species  of  Staurastrum :   A.  Staurastrum  vestitum.     B.  Stau- 
rastrum  aculeatum  ;  C.  Staurastrum  paradoxum  ;  D.  E.  Staurastrum  brachiatum. 

Some  species  have  spiny  projections  of  the  outer  coat, 
which  is  of  a  horny  consistence,  as  in  Fig.  28.  Others  are 
notched  on  the  sides ;  some,  as  the  Closterium,  (Fig.  29.) 


FIG.  29. — Economy  of  Closterium  lumilci  :  A.  Frond  showing  central  separation  at  a, 
in  which  large  globules,  £,  are  not  seen.  B.  One  extremity  enlarged,  showing  at  a  the 
double  row  of  cilia,  at  b  the  internal  current,  and  at  c  the  external  current.  C.  External 
jet  produced  by  pressure  on  the  frond.  D.  Frond  in  a  state  of  self-division. 

8* 


THE  SCIENCE  OF  LIFE. 


are  smooth.  In  the  latter  a  circulation  of  fluid  may  be 
seen  between  the  cellulose  coat  and  the  "  primordial 
utricle."  (Chap.  IV,  Sec.  6.)  Some  consider  this  circula- 
tion to  be  caused  by  cilia,  but  it  is  rather  doubtful.  We 
are  inclined  to  regard  it  as  an  exhibition  of  the  molec- 
ular motion  of  bioplasm  already  described.  Many  of 
the  Desmids  multiply  by  subdivision,  but  the  plan  is 
modified  so  as  to  maintain  the  symmetry  characteris- 
tic of  the  tribe.  At  other  times  multiplication  takes 
place  by  the  subdivision  of  the  endochrome  into  gran- 
ular particles,  or  "  gonidia,"  set  free  by  rupture  of  the 
cell-wall. 

The  process  of  conjugation  differs  from  that  of  Palmo- 
glaea,  since  each  cell  has  a  firm  external  envelope,  which 
cannot  coalesce  with  another.  In  Cosmarium,  (Fig.  30,) 

for  example,  the  conjugating 
cells  become  deeply  cleft 
and  separate,  so  that  the 
contents  pour  out  freely,  at 
first  without  a  protecting 
membrane.  At  length  it 
acquires  an  envelope,  and 
becomes  a  sporangium,  or 
spore-case,  of  reddish-brown 
tint.  It  is  covered  with 
spines,  and  greatly  resem- 
.  bles  certain  fossil  forms 

ric.  30. — Cosmanum  botrytts :  A.  Ma- 
ture frond.  B.  Empty  frond.  C.  Transverse   found    in    flint    called    Xan- 
view.    D.  Sporangium,  with  empty  fronds. 

thidia.  The  Clostena  con- 
jugate after  a  somewhat  similar  manner,  and  it  is 
not  uncommon  to  find  a  pair  in  this  condition,  but 


PROTOPHYTES.  91 

their  sporangia  are  smooth  instead  of  tuberculated  or 
spiny. 

8.  The  families  of  Algae,  called  Oscillator  iacece,  Nosto- 
chacece,  Confervacece,  and  Conjugates,  may  all  be  consid- 
ered as  Protophytes,  but  a  brief  description  only  can  be 
given  here.  The  structure  is  generally  microscopic. 

The  Oscillatoria  are  tubular  filaments  with  partial 
subdivisions,  formed  by  the  elongation  of  their  primor- 
dial cells,  occurring  in  fresh  and  salt  water,  and  on  damp 
ground.  They  have  very  curious  movements,  sometimes 
swaying  like  a  pendulum,  and  at  others  bending  at  the 
extremity  from  one  side  to  another,  or  moving  straight 
onward. 

Nostocs  are  beaded  filaments  lying  in  masses  of  green- 
ish gelatinous  matter.  As  the  jelly  forms  rapidly  in 
damp  weather,  they  have  been  termed  "  fallen  stars." 
The  alchemists  often  refer  to  this  substance,  and  it  enters 
into  many  of  their  recipes  for  the  pretended  transmuta- 
tion of  metals. 

The  Conferva  may  be  found  in  almost  every  pond  or 
ditch,  but  are  especially  abundant  in  running  water. 
They  constitute  the  greater  part  of  those  green  threads 
which  are  found  in  streams,  or  near  the  sea-shore.  Each 
thread  is  a  long  cylinder,  in  which  the  endochrome,  of  a 
green,  brown,  or  purplish  hue,  is  either  distributed  uni- 
formly through  the  cell,  or  arranged  in  a  net-work,  or 
spiral  form.  It  increases  by  binary  subdivision  in  the 
terminal  cell,  as  well  as  by  zoospores  produced  within 
the  cells. 

The  family  Conjugates  is  so  called  because  the  fila- 
ments are  so  constantly  yoked  together.  They  are 


92 


THE  SCIENCE  OF  LIFE. 


generally  found  in  still  water.  In  an  early  stage  of 
growth  the  endochrome  is  diffused  through  their  cavi- 
ties, but  after  a  time  arranges  itself  in  regular  spirals. 
Then  adjacent  cells  put  forth  protuberances  which  coa- 
lesce, and  a  passage  is  formed  between  the  cells.  The 
endochrome  of  one  cell  passes  over  into  the  cavity  of  the 
other,  forming  a  sporangium,  or  spore-case.  (Fig.  31.) 


FIG.  31. — Various  stages  of  the  history  of  Zygnema  quininum  :  A.  Three  cells,  «,  £,  r, 
of  a  young  filament,  of  which  b  is  undergoing  subdivision  :  B.  Two  filaments  in  the  first 
stage  of  conjugation,  showing  the  spiral  disposition  of  their  endochromes,  and  the  protu- 
berances from  the  conjugating  cells.  C.  Completion  of  the  act  of  conjugation,  the  endo- 
chromes of  the  cells  of  the  filament  a  having  entirely  passed  over  to  those  of  filament  £, 
in  which  the  sporangia  are  formed. 

9.  The  most  beautiful  and  interesting  unicellular  forms, 
now  generally  conceded  to  be  vegetable,  are  found  among 
the  Diatomacece.  Their  motions  caused  many  to  regard 
them  as  animals,  but  naturalists  now  agree  in  calling 
them  Protophytes.  They  are  called  Diatoms  because 
of  their  extreme  brittleness  and  the  ease  with  which 
a  chain  of  them  may  be  broken  into  its  component  cells. 
Like  the  Desmids,  they  are  simple  cells  containing  endo- 


PROTOPHYTES.  93 

chrome,  with  a  firm  external  covering.  In  the  Diatoms, 
however,  this  envelope  is  consolidated  by  silex,  or  flinty 
matter,  sometimes  also  by  iron.  The  silicious  envelope 
of  each  "  frustule,"  or  cell,  is  covered  with  most  elabo- 
rate and  beautiful  marking,  and  consists  of  two  valves, 
or  plates,  closely  applied  to  each  other,  like  the  valves  of 
a  Mussel,  along  a  suture,  or  line  of  contact.  If  the  valve 
is  hemispherical,  the  cavity  will  be  globular;  if  a  segment 
of  a  sphere,  the  cavity  will  be  lenticular.  Sometimes 
the  central  part  is  flattened,  and  the  sides  turned  up,  so 
that  the  valve  resembles  the  cover  of  a  pill-box,  in  which 
case  the  cavity  will  be  cylindrical.  Then,  again,  the 
valve  may  be  square,  triangular,  round,  heart-shaped, 
boat-shaped,  etc.  In  many  species  of  Diatoms  the 
markings  are  so  minute  that  they  can  only  be  made  out 
with  the  highest  powers  of  the  microscope ;  in  others  a 
very  moderate  power  suffices  to  exhibit  the  lines  and 
dots  in  patterns  which  rival  the  most  elaborate  works  of 
art.  (Figs.  32,  33,  34.) 

In  the  living  state  Diatoms  are  found  abundantly  in 
every  pond,  rivulet,  ocean,  and  rock-pool.  In  some 
parts  of  the  world  they  form  immense  deposits. 

A  mud  bank  in  Victoria  Land,  400  miles  long  and  120 
broad,  is  composed  of  silicious  valves  of  Diatoms.  In 
Sweden  and  Norway,  under  the  name  of  bergh-mehl, 
they  are  used  for  mixing  with  flour  for  bread  in  seasons 
of  scarcity.  Under  the  cities  of  Richmond  and  Peters- 
burgh,  Virginia,  is  a  deposit  twenty  feet  thick,  while  the 
polishing  slate  of  Bilin  contains  Diatoms  so  small  that  in 
a  single  cubic  inch  4O,ooo,ooo,cxx),ooo  (forty  trillions)  are 
found. 


94 


THE  SCIENCE  OF  LIFE. 


FIG  32. — Arachnoidiscus  Ehrenbergii. 

The  Arachnoidiscus  Ehrenbergii,  (Fig.  32,)  is  common 
on  the  coast  of  California,  attached  to  sea-weed.  Its  gen- 
eral appearance 
is  that  of  a  glas- 
sy pill-box.  The 
figure  shows  one 
of  the  ends,  or 
frustules,  covered 
with  delicate  tra- 
cery like  a  spi- 
der's web,  by 
which  the  genus 
gets  its  name, 
from  arachne,  a 
spider,  and  disc- 
us, a  disk.  FlG-  33 -Heliopelta. 


PROTOPHYTES. 


95 


The  Hdiopelta,  sun-shield,  (from  helios,  the  sun,  and 
pelta,  a  shield,  (Fig.  33,)  is  a  most  beautiful  disk,  whose 
markings  form  a  regular  star,  the  number  of  whose  rays 
determine  the  species. 

The  Diatoma  vulgare,  (A.,  Fig.  34,)  is  a  quite  common 


FIG.  34.— A.  Diatoma  vulgare :  a.  Side  view  of  frustule  ;  b.  Frustule  undergoing 
self-division.  B.  Grammatophora  serpentina.  a.  Front  and  side  views  of  single  frus- 
tule. b.  b.  Front  and  end  views  of  divided  frustule.  c,  A  frustule  about  to  undergo  self- 
division.  </.  A  frustule  completely  divided.  C.  Isthmia  nervosa. 

form.  The  frustules  often  hang  together,  forming  zig- 
zag chains  by  rapid  self-division. 

Some  species  of  Grammataphora  have  delicate  striae 
on  the  borders  of  each  valve,  which  are  used  as  tests  of 
microscopic  excellence. 

The  Isthmia  nervosa  has  a  remarkable  areolated 
structure,  which  will  repay  careful  examination.  In  its 
growth  two  cells  form  within  the  valves,  and,  as  they 


96  THE  SCIENCE  OF  LIFE. 

enlarge,  break  forth,  but  the  silicious  hoop  which  joined 
the  new  frustules  to  the  old  one  remains  attached  for  a 
time  round  one  of  them,  causing  some  to  appear  trunc- 
ated instead  of  round. 

The  genus  Navicula  is  so  called  from  its  resemblance 
to  a  boat  or  little  ship,  (naus,  a  ship.)  They  are  found 
both  living  and  in  a  fossil  state.  Some  are  striped  lon- 
gitudinally, and  some  transversely  ;  some  are  shaped  like 
an  old-fashioned  letter  S,  as  the  Pleurosigma,  in  which 
the  striae  are  resolved  by  a  highly  magnifying  power  into 
hexagonal  dots. 

10.  In  the  Protophytes  we  see  the  endowments  of 
simple  vegetable  cells.  A  piece  of  bioplasm,  or  living 
tissue,  transforms  its  outer  layer  into  cellulose,  and 
forms  chlorophyll  or  starch  in  its  interior,  absorbing  new 
pabulum  continually,  and  casting  off  the  old  effete  atoms. 
The  relationship  of  each  family  is  seen  by  these  func- 
tions common  to  all.  Each  species  of  each  family  has, 
however,  its  own  peculiarities,  which  distinguish  it  from 
all  others.  The  Protococci  remain  rounded  cells,  but 
the  Oscillatoria,  Confervaceae,  etc.,  have  an  instinct  for 
elongation,  so  that  they  become  tubular,  and  for  distrib- 
uting endochrome  in  characteristic  spiral  patterns,  vary- 
ing in  each  species,  while  the  Diatoms  appropriate  silica 
from  their  pabulum  to  harden  the  cellulose  envelope, 
and  arrange  it  in  their  frustules  atom  by  atom,  each 
species  after  its  own  pattern,  and  all  with  marvelous 
regularity  and  beauty.  The  Monistic  theory  of  the 
universe  has  no  satisfactory  reason  to  give  for  the  exist- 
ence of  such  varied  tendencies.  Schleiden  has  well  said, 
"  We  do,  indeed,  see  into  the  mechanism  of  the  puppet ; 


PROTOPHYTES.  97 

but  who  holds  the  strings  and  directs  all  its  motions  to 
One  Purpose?  Here  closes  the  office  of  the  naturalist; 
he  turns  from  the  world  of  space  and  lifeless  matter 
upward  to  where,  in  holy  anticipation,  we  seek  the  Ruler 
of  worlds."  * 

*  Schlieden's  "  Poetry  of  the  Vegetable  World." 


98  THE  SCIENCE  OF  LIFE. 


CHAPTER  VII. 

THALLOGEN3. 

Thus  Nature  varies  ;  man  and  brutal  beast, 
And  herbage  gay,  and  silver  fishes  mute, 
And  all  the  tribes  of  heaven,  o'er  many  a  sea, 
Through  many  a  grove  that  wing,  or  urge  their  so:ig 
Near  many  a  bank  of  fountain,  lake,  or  rill, 
Search  where  thou  wilt,  each  differs  in  his  kind, 
In  form,  in  figure  differs. — LUCRETIUS. 

1.  THALLUS-PLANTS,  called  also  Thallogens,  or  Thai- 
lophytes,  (from  thallos,  a  frond,  or  green  leaf;  genein, 
to  produce,  phyton,  a  plant,)  have  no  true  vascular  sys- 
tem, but  are  composed  of  cells  of  various  sizes,  forming 
membranous  expansions,  or  filaments  more  or  less  sim- 
ple, branched,  or  interlacing.     They  differ  from  Proto- 
phytes  by  the   more  intimate   union  of  cells  in  their 
structure.     In  some  of  the  Protophytes  there  is  an  ad- 
hesion of  the  cells  by  a  fusion  of  their  gelatinous  invest- 
ment, yet  each  cell  is  a  repetition  of  the  former  one,  and 
is  capable  of  living  independently  if  detached,  so  that 
each  answers   to   the   designation   of  a   unicellular,    or 
single-celled  plant.     In  the  Thallogens  the  cells  are  not 
only  closely  united,  but  exhibit  a  differentiation  in  struct- 
ure or  function,  and  a  relation  of  mutual  dependence, 
constituting  each  plant  (not  each  cell)  an  individual. 

2.  The  higher  Alga,  or  Sea-weeds,  the  Lichens ,  and 
the  Fungi  may  be  regarded  as  Thallophytes,  although 


THALLOGENS.  99 

some  species  may  present  many  points  of  resemblance 
with  the  simple  Protophytes. 

3.  The  ALG^E,  or  Sea-weeds,  have  been  divided  into 
three  orders,  the  Red,  the  Olive,  and  the  Green  Sea- 
weeds— Rhodospermeae,  Melanospermeae,  and  Chloros- 
permeae.  "  The  latter  order  generally  includes  the  Con- 
fervoid  and  other  families  which  we  have  considered  as 
unicellular  plants.     When  we  examine  the  higher  Sea- 
weeds, we  find  a  certain  foreshadowing  of  the  distinction 
between  Root,  Stem,  and  Leaf,  which  is  characteristic 
of  still  higher  types.     This  sort  of  unconscious  prophecy 
of  higher  forms  to  come  is  by  no  means  uncommon  in 
other  classes  both   of  plants  and  animals,  and  affords 
another  proof  that  living  things  have  been  formed  on 
an   intelligent   plan.      In  the   Sea-weeds,  however,   the 
apparent  distinction  of  stem  and  root  serves  for  little 
else  than  the  mechanical  attachment  of  the  plant.    There 
is  no  departure  from  the  cellular  type,  the  only  modifi- 
cation being  that  the  layers  of  cells  are  of  different  sizes 
and  shapes. 

4.  The  Olive  Sea-weeds,  or  Fucoids,  (Melanospermce^ 
often  grow  to  a  considerable  size,  attached  by  sucker-like 
roots  to  the  rocks,  and,  in  some  cases,  buoyed  up  by  air- 
bladders.     Others  are  parasitical.     The  fructification  of 
many  species  in  this  group  is  sexual.     In  the  common 
bladder-wrack,  Fucus  vesiculosus,  the  reproductive  organs 
are  on  different  plants,  but  in  other  species,  as  Fucus 
senatus,  they  are  both  together,  the  one  olive-green,  the 
other  orange-yellow.     The  "  receptacles  "  are  at  the  ex- 
tremities of  the  fronds,  and  may  be  known  to  be  mature 
by  each  discharging   little   gelatinous  masses  adhering- 


100 


THE  SCIENCE  OF  LIFE. 


round  its  orifice.     If  now  a  section  is  made  through  it, 
it  will  be  seen  to  be  a  cavity  lined  with  filaments,  some 

of  which  p r o j e c t 
through  the  pore. 
The  filaments,  or  an- 
theridia,  are  chains 
of  cells  containing 
antlierozoids.  These 
are  yellow  oval  bod- 
ies, with  two  thread- 
like appendages, 
which,  when  liber- 
ated by  the  bursting 
of  the  cell,  have  a 
spontaneous  and  rap- 
id motion  around  the 
sporangia,  (or  parent 
cells  of  the  germs,) 
which  they  fecun- 
date. These  sporan- 
gia are  pear-shaped 
bodies  lying  near  the 

fiG.  35. — section  of  receptacle  of  Fiicus  platycarpus, 
lined  with  filaments  containing  antheridial  cells  and  walls  of  the  Cavity,  Or 

sporangia. 

receptacle,  and  each 

one  produces,  by  fission,  a  cluster  of  eight  cells,  or  octo- 
spores.     (Fig.  35.) 

5.  Among  the  red  Sea-weeds,  or  Rhodospermecz,  are 
various  simple  but  beautiful  forms,  eagerly  sought  for  by 
sea-side  collectors  for  albums.  They  live  generally  in 
deeper  water  than  other  sea-weeds,  and  show  their  rich- 
est tints  when  growing  in  the  shade.  The  genus  Poly- 


THALLOGENS.  101 

siphonia  contains  many  species,  some  small  and  delicate, 
or  long  and  filmy,  and  of  various  tints  of  brown  or  vio- 
let. The  fronds  are  thread-like  and  jointed  ;  the  joints 
striped,  since  the  stem  is  composed  of  parallel  tubes  or 
siphons,  from  whence  its  name,  (poly,  many ;  siphon, 
tube.)  The  fructification  is  twofold,  on  distinct  plants: 
i.)  Ceramidia,  or  urn-shaped  cells  containing  pear-shaped 
spores;  2.)  Tetraspores,  or  groups  of  four  spores,  imbed- 
ded in  swollen  branchlets.  The  genus  Ceramium  is 
thread-like,  jointed,  branched,  with  repeated  forkings. 
The  tips  of  the  filaments  are  always  forked,  and  often 
curl  toward  each  other.  The  fruit  is  of  two  kinds : 
I.)  Berries,  or  capsules,  containing  seeds,  and  called 
favellce.  2.)  Tetraspores,  or  groups  of  four  seeds,  im- 
mersed in  the  substance  of  the  branch,  and  surrounding 
it  in  a  whorl.  Another  beautiful  and  not  uncommon 
genus,  found  at  low-water  mark,  or  cast  up  after  a  storm, 
is  Ptilota,  (from  a  Greek  word  signifying  "  pinnated.") 
It  has  many  small  branches,  or  pinnae,  and  these  again 
are  cut  into  smaller  divisions,  or  pinnula.  At  the  top  of 
the  latter  is  the  fructification,  consisting  of  minute  cap- 
sules, or  favellce.  Some  plants  also  contain  tetraspores. 
Corallines  are  a  family  of  red  Sea-weeds  whose  tissue  is 
consolidated  by  calcareous  deposit.  The  arrangement  of 
tetraspores  in  the  red  Algae  is  illustrated  by  Fig.  36. 

6.  The  class  of  LICHENS  consists  of  cellular  plants  of 
very  simple  structure.  They  form  irregular  patches, 
generally  dry,  upon  stones,  trees,  etc.,  which  they  deco- 
rate with  various  colors.  They  are  found  in  all  climates. 
Some  are  used  in  medicine,  as  the  Iceland  Moss,  (Cetra- 

ria  Islandica;}  others,  as  the  Orchil,  produce  a  valuable 
9* 


IO2 


THE  SCIENCE  OF  LIFE. 


dye,  and  one  species,  Leonora  esculenta,  found  in  the 
Desert  of  Tartary,  seems  to  fall  from  the  sky  as  a  mirac- 
ulous manna.  Men  and  beasts  may  be  nourished  on  it. 


FIG.  36.— Arrangement  of  tretraspores,  in  Carpocaulon  mediterraneum  :  A.  Entire 
plant.  B.  Longitudinal  section  of  branch.  (N.  B.  Where  only  three  tretraspores  are  seen 
it  is  merely  because  the  fourth  did  not  happen  to  be  so  placed  as  to  be  seen  at  the  same 
view.) 

It  is  in  the  form  of  globules,  varying  from  the  size  of  a 
pin's  head  to  that  of  a  hazel  nut ;  and  as  it  grows  freely, 
not  being  attached  to  any  substance,  it  is  readily  driven 
by  the  wind  from  one  place  to  another. 

The  thallus  of  Lichens  may  be  of  various  sizes,  forms, 
and  colors.  (Fig.  37.)  Its  fruit  is  called  Apotheceia,  and 
forms  cups,  or  shields,  of  various  forms,  often  colored 
bright  red,  yellow,  gray,  or  black.  When  these  are  di- 
vided by  vertical  sections  they  are  found  to  contain  a 


THALLOGENS.  103 

number  of  asci,  or  spore-cases,  arranged  vertically  among 
filaments  which  are  termed  paraphyses.     The  fecundating 


a  b  f  g          d  e  c 

FIG.  37. — Lichens,  a.  Cladonia,  with  scarlet  conceptacles.  b.  Usnea.  c.  Sticta. 
d.  Parmelia.  e.  Vertical  section  of  receptacle,  f.  Same  highly  magnified,  with  thecse 
and  paraphyses.  g.  Double  spore. 

apparatus  is  called  the  Spermogonia,  and  consists  of  small 
rounded  or  oblong  organs,  lodged  in  particular  tubercles 
or  immersed  in  the  superficial  layers  of  the  thallus.  The 
cellular  filaments  of  the  spermagonia  give  off  minute 
oval  bodies,  called  spfrmatia,  which  are  analogous  to  the 
antherozoids  of  Algae,  but  differ  in  being  destitute  of 
spontaneous  motion. 

7.  The  FUNGI  form  an  extensive  class  of  primitive 
organisms,  generally  ranked  as  plants,  but  which  have 
so  many  peculiarities  as  to  entitle  them  to  be  considered 
apart.  We  should  not  greatly  err  if  we  regard  them 
as  a  third  type  of  living  things,  differing  both  from  ani- 
mals and  vegetables.  They  have  no  chlorophyll,  as  green 
vegetables  have,  and  which  enables  them  to  break  up 
carbonic  acid.  (Chap.  VI,  Sec.  2.)  Light  is  not  essen- 
tial to  the  activity  of  Fungi,  as  it  is  to  that  of  vegeta- 
bles. They  are  incapable  of  assimilating  inorganic  food, 
but  live  upon  organic  substances.  They  are  the  agents 
of  fermentation  and  of  putrefaction,  and  their  principal 


104 


THE  SCIENCE  OF  LIFE. 


office  seems  to  be  to  break  down  and  to  restore  to  the 
inorganic  world  the  effete  formed  material  of  animal 
and  vegetable  life.  Mushrooms,  Puff-balls,  Molds,  and 
the  Rust  of  grain  are  examples  of  Fungi. 

8.  The  simplest  forms  of  Fungi  resemble  Protophytes, 
except  in  the  absence  of  chlorophyll,  either  green  or  red. 
Recent  investigations  have  indicated  that  those  which 
seem  most  simple  are  but  imperfectly  developed  states 
of  other  species.  The  Torula  cerevisicz,  or  yeast-plant, 
which  is  the  cause  of  fermentation  in  solutions  of  sugar, 


FIG.  38. — Appearances  presented  by  Bacteria  under  the  microscope.  At  c,  are  iso- 
lated Bacteria  ;  at  d,  they  are  arranged  round  a  center  ;  while  at  a  they  appear  in  long 
strings  ;  at  e  is  observed  a  solitary  torula.  All  highly  magnified. 

and  Bacteria  (Fig.  38)  of  various  forms,  which  cause  pu- 
trefaction in  animal  substances,  appear  to  be  varieties,  or 
stages,  in  the  development  of  some  of  the  u  molds,"  or 
microscopic  fungi,  many  of  which  are  capable  of  poly- 
morphism, or  the  assumption  of  many  forms.  In  some 
kinds  of  fungi  the  bioplasm  shows  amceboid  movements, 
having  a  great  resemblance  to  some  of  the  lower  forms 
of  animal  life. 

9.  Fungi  are  cellular  organisms  of  variable  consistence. 
They  exhibit  two  well-defined  structures,  a  mycelium,  or 
spawn,  (Gr.  myces,  a  fungus,)  formed  of  filaments  some- 


THALLOGENS.  105 

times  assuming  a  membraneous,  a  tubercular,  or  a  pulpy 
form,  and  a  fruit,  or  reproductive  structure,  which  dif- 
fers in  different  tribes.  The  essential  reproductive  or- 
gans are  spores,  called  also  conidia,  usually  four,  or  some 
multiple  of  four,  attached  to  the  cellular  tissue,  and  sup- 
ported on  simple  or  branched  filaments,  (called  conidio- 
phores,  or  basidia,}  or  contained  in  sacs,  (theca,  cystidia, 
or  asci ;  all  of  which  words,  derived  from  the  Greek, 
have  similar  meaning.) 

10.  Fungi  have  been  divided  into  six  orders,  as  follows  : 

i.)  Hymenomycetes,  (Gr.  hymen,  a  membrane,  and  myces, 
a  fungus.)  Mycelium  inconspicuous,  bearing  fleshy  fruits 
which  expand  so  as  to  expose  the  spore-bearing  mem- 
brane to  the  air.  Mushrooms  are  well-known  examples. 

2.)  Gasteromycetes,  (Gr.gaster,  belly.)  Fructifying  sur- 
face inclosed,  as  in  Puff-balls. 

3.)  Coniomycetes,  (Gr.  konis,  powder.)  The  spawn  or 
vegetative  part  is  reduced  to  a  minimum,  and  the  abun- 
dant spores  form  a  dusty  or  sometimes  a  gelatinous 
mass.  The  rust  and  bunt  of  wheat  and  other  grains  are 
instances. 

4.)  Hyphomycetes,  (hyphao,  to  weave.)  The  vegetative 
part  consists  mostly  of  loose  threads,  as  the  naked  seed 
Molds. 

5.)  Ascomycetes,  (askos,  a  bag.)  The  sacs,  or  asci,  con- 
taining the  sporidia  are  either  packed  into  an  exposed 
hymenium,  or  line  the  interior  of  the  fruit-bearing  cysts, 
as  Truffles,  etc. 

6.)  Physomycetes,  (physa,  a  bladder.)  Mycelium  fila- 
mentous, bearing  sacs,  containing  minute  iporules,  as  the 
common  Bread-mold. 


io6  THE  SCIENCE  OF  LIFE. 

11.  The  difficulty  of  determining  what  forms  are  to  be 
regarded  as  species,  and  what  as  mere  varieties,  finds 
many  illustrations  in  the  class  of  Fungi.     We  know  but 
little  of  the  influence  of  external  conditions  in  modifying 
forms,  and  the  forms  of  fungi  are  so  exceedingly  unsta- 
ble that  the  best  observers  are  often  at  a  loss.     Yet  this 
variability  is  only  one  of  degree,  since  all  living  beings  are 
more  or  less  subject  to  modifications  of  form  by  external 
influences.     It  is  this  variability  which  has  rendered  the 
Darwinian  hypothesis  of  evolution  by  "  the  survival  of 
the  fittest "  so  plausible  a  theory.     But  notwithstanding 
this  capability  of  modification,  there  is  still  a  certain  fun- 
damental and  specific  type  for  each  assemblage  of  forms, 
and  the  amount  of  variability  is  strictly  limited. 

12.  Many  diseases  of  plants  and  animals  are  associated 
with  the  growth  of  Fungi.     The  "  mildew  "  (Puccinid) 
and  "  rust "  (Uredo)  of  wheat,  etc.,  the  potato  blight, 
(Peronospora,)  the  disease  in  Silk-worms  called  Muscar-- 
dine,  (Botrytis,)  the  false  membrane  in  diphtheria,  the 
white  patches  in  aphthae,  or  thrush,  and  many  skin  af- 
fections, afford  examples.    Pyaemia  is  supposed  to  result 
from  bacteria  in  the  blood,  and  many  epidemic  diseases 
have  been  ascribed  to  similar  origin.     The  prevalence  of 
atmospheric  changes,  however,  and  variations  in  external 
conditions,  as  light,  heat,  moisture,  etc.,  have  much  to 
do  in  predisposing  both  animal  and  vegetable  tissues  to 
disease,  and  in  producing  epidemics.     Since  the  office 
of  Fungi  is  to  remove  decaying  or  effete  organic  matter, 
we  must  discriminate  between  those  diseased  conditions 
which  provide  a  habitat  for  fungi  and  the  effects  pro- 
duced by  the  fungi  themselves 


THALLOGENS.  107 

13.  The   excessively  minute  and   almost   vapor-like 
sporules  of  fungi  float  about  in  the  atmosphere  in  count- 
less numbers,  only  waiting  for  a  fitting  soil  in  which  to 
grow.     As  long  as  there  is  no  refuse  matter  to  be  re- 
moved these  scavengers  are  unemployed,  but  the  small- 
est quantity  of  decaying  animal  or  vegetable  matter  left 
exposed  becomes  covered  with  spores,  which  develop 
with  astonishing  rapidity.     A  scanty  number  of  spores, 
only  to  be  detected  by  careful  research,  will  in  a  few 
days,   and  sometimes  in  a  single  night,  give  birth  to 
myriads,  to  repress  or  remove  the  nuisances  referred  to. 
When  the  offal  diminishes  fewer  of  the  spores  find  soil 
on  which  to  germinate,  and  when  all  is  consumed  the 
active   legions   return   to  their   latent   or   undeveloped 
state.     Like  Milton's  spirits — 

So  thick  the  aery  crowd 

Swarmed  and  were  straitened  ;  till,  the  signal  given, 
Behold  a  wonder  ;  they  but  now  who  seemed 
In  bigness  to  surpass  earth's  giant  sons, 
Now  less  than  smallest  dwarfs. 

14.  In  the  chapter  on  the  Protophyte  type  of  vegeta- 
ble life,  we  considered  the  bioplasm,  or  living  matter, 
differing  in  each  kind,  yet  agreeing  in  one  particular, 
namely,  that  each  cell  exhibits  a  repetition  of  the  form 
and  power  of  the  parent-cell.    In  the  Thallogens  we  find 
another  idea  predominating,  or  rather  two  leading  ideas, 
the  co-ordination  of  many  cells  in  the  structure  of  one 
individual,  and  the  differentiation  of  cells  in  form  and 
function,  analogous  to  the  division  of  labor  in  human 
society.     Respecting  the  first,  Joseph  Cook  has  well  re- 
marked, in  his  axiomatic  style :  "  Living  tissues  are  co- 


io8  THE  SCIENCE  OF  LIFE. 

ordinated  according  to  definite  plans.  As  every  change 
must  have  an  adequate  cause,  we  are  compelled  to  infer 
the  existence  of  a  co-ordinating  force  behind  the  action 
of  the  bioplasts  in  each  organism.  That  force  is  the 
cause  of  form  in  organisms.  It  has  as  many  types  as 
there  are  types  of  organisms,  vegetable  and  animal."  * 
The  same  subtle  power  which  co-ordinates,  also  differen- 
tiates the  cells.  This  power  resides  in  the  original  germ, 
before  the  organization  of  the  individual  form,  and  is 
what  we  have  already  defined  as  Life,  and  is  not  explica- 
ble by  physical  causes.  "Collocation  of  parts  in  an 
organism  is  precisely  what  materialism  has  never  yet 
explained."  f 

*  "  Heredity,"  by  Joseph  Cook,  p.  46.  f  Cook's  "  Biology." 


ACROGENS.  100 


CHAPTER  VIII. 

ACROGENS. 

Flower  in  the  crannied  wall, 

I  pluck  you  out  of  the  crannies, 

Hold  you  here  in  my  hand, 

Little  flower,  root  and  all, 

And  if  I  could  understand 
What  you  are,  roots  and  all,  and  all  in  all, 
I  should  know  what  God  and  man  is. 

— TENNYSON. 

1.  IN  the  type  of  Acrogens  the  instinct  of  develop- 
ment, or  evolution  of  cells,  is  seen  only  at  the  summit 
or  apex  of  the  stem.     Cells  in  other  parts  of  the  plant 
may  enlarge,  but  do  not  multiply  themselves.     These 
plants  generally  have  distinct  stems  and  leaves,  with 
stomata,  (Chap.  IV,  Sec.  n,)  a  certain  amount  of  vascu- 
lar tissue,  (Chap.  IV,  Sec.  10,)  and  theca,  or  cases  con- 
taining spores.     The  Stoneworts,  (Characcej)  the  Liver- 
worts,   (Hepaticce^)   the    Horsetails,    (Equisetacecs^)    the 
Ferns,  (Filices])  and  the  Mosses,  (Musci^)  are  the  prin- 
cipal families  of  Acrogens. 

2.  The  Stoneworts  (CHARACE^E)  have  generally  been 
regarded  among  Algae,  or  water-weeds.     But  they  differ 
greatly  from  Algse  in  having  a  distinct  axis  of  growth, 
and  appendages.     The  axis  may  be  a  simple  tube,  (Ge- 
nus Nitella^}  or  a  tube  with  a  cortical  layer  of  smaller 
tubes  surrounding  it,  (Genus  Chara^)     They  are  found 
in  ponds  and  rivers,  in  tangled  masses  of  a  dull  green 
color.     Each  plant  is  hardly  thicker  than  a  stout  needle, 

10 


110 


THE  SCIENCE  OF  LIFE. 


but  may  be  three  or  four  feet  long.  It  has  rootlets 
springing  from  the  axis,  by  which  it  is  fixed  in  the 
muddy  bottom  of  the  stream,  etc.,  but  the  main  source 
of  its  nutriment  is  the  water  in  which  it  lives.  It  pos- 
sesses chlorophyll,  and  in  consequence  decomposes  car- 
bonic acid  under  sunlight,  retaining  the  carbon  to  form 
part  of  its  own  substance,  and  giving  off  the  oxygen. 
The  branchlets  (or  leaves,  as  they  are  called)  are  grouped 
in  whorls,  or  spring  from  the  same  height  in  the  stem. 


FIG.  39.—  Nitella  flexilis  :  A.  Stem  and  branches  of  the  natural  size.  a.  b.  c.  d.  Four 
verticils  of  branches  issuing  from  the  stem.  e.f.  Subdivision  of  the  branches.  B.  Portion 
of  the  stem  and  branches  enlarged,  a.  b.  Joints  of  stem.  c.  d.  Verticils,  e.f.  New  cells 
sprouting  from  the  sides  of  the  branches,  g.  h.  New  cells  sprouting  at  the  extremities  of 
the  branches. 

and  at  regular  intervals.     (Fig.  39.)     The  main  stem  is 
called  the  axis,  and  a  branch,  when  it  exists,  is  a  second- 


ACROGENS. 


Ill 


ary  stem.  The  appendages  are  the  leaves,  branches, 
rootlets,  and  reproductive  organs.  The  points  on  the 
axis,  or  stem,  from  which  the  appendages  spring,  are 
called  nodes,  the  intervening  parts  being  the  internodes. 
In  Chara  the  internodes  have  a  spiral  striation.  Growth 
takes  place  at  the  apex  by  the  development  of  new 
nodes  and  internodes.  Each  internode  is  formed  by  the 
growth  and  elongation  of  one  cell. 

The  terminal  bud  is  formed  by  a  single  cell,  which  di- 
vides by  fission  into  two,  one  of  which  forms  the  inter- 
node,  while  the  other  sub- 
divides into  lateral  cells, 
which,  by  division,  produce 
the  appendages.  In  the  lat- 
ter, after  a  certain  stage, 
the  terminal  cell  is  inca- 
pable of  further  division, 
but  in  the  stem  the  proc- 
ess continues  indefinitely. 
.  40.) 


FIG.   40. — Growing  Point   of  Chara. 
The   reproductive   Organs     <*.  Terminal    cell    dividing,     b.  Cells  form 
,  ing  youngest  node,  and  which  by  their  fis. 

in  these    plants    are    Of   tWO     sion  will  give  rise  to  a  whorl  of  appendages. 
i   •     j  i          .  •  c.  c.  Internodal  cells,    d.  Incipient  append- 

kinds,    oval    sporangia,    or  agss.  ,.  Same  farther  advanc^  £££ 
spore-fruits,  and  antheridia.   ™"ai  ceil  dividing. 
The  latter  are  smaller  than  the  sporangia,  and  globular, 
and  contain  filaments  whose  cells  are  changed  into  little 
ciliated  bodies  called  anther ozoids,     (Fig.  41.) 

The  growing  spore  from  the  sporangium  gives  off  two 
filaments  resembling  the  hyphse  in  fungi,  one  of  which 
serves  as  a  temporary  root,  and  a  cell  in  the  other  pro- 
duces a  group  of  lateral  projections  from  which  the  young 


112 


THE  SCIENCE  OF  LIFE. 


Chara  springs.     This  temporary  structure  is  termed  the 
pro-embryo. 

In  Chara  vulgaris  the  circulation,  or  movement,  of 
bioplasm  in  vegetables  was  first 
discovered.  (Chap.  II,  Sec.  7, 
and  Chap.  IV,  Sec.  6.) 

3.  The  Liverworts,  or  HEPA- 
TIC^, form  a  class  or  group  of 
plants  generally  considered  in- 
termediate between  Lichens 
and  Mosses.  They  are  fur- 
nished with  leaves,  or  lobed 
fronds,  with  rootlets  on  the 
F.G.  4i.-portion  of  Antheridium  under  surface,  which  send  up 

of  Chara.     x.  Several  jointed  filamnts  jfc  -  •    {  d 

attached  to  a  vesicle.      2.  End  of  one  J       o 

of  the  tubes,  a  spiral  thread  escaping,    shield-like    disks,    bearing   an- 

3.  A  tube  nearly  empty.     4.  An  an- 

therozoid  with  its  cilia.  theridia,    or    radiating    bodies, 

bearing  at  first  archcgonia,  or  female  organs,  and  after- 
ward sporangia,  or  spore-cases.     (Fig.  42.) 

The  arrangement  of 
the  stomata,  or  breath- 
ing pores,  in  these  hum- 
ble plants  is  far  more 
complex  than  we  find 
it  in  others.  The  leaves 
of  all  the  higher  plants 
have  cavities,  or  air- 

SDaCCS         Communicating 

*• 
with    the    external   WOrld 

by    openings,    or   pores,   which  are    guarded  by   elastic 
cells  ;    but   in    Marchantia   polymorpha  the    green    sur- 


FIG.  42.—  Frond  of  Marchantia  polymorpha, 
with  gemmiparous  conceptacles,  and  lobed  re- 
ceptacles  bearing  pistillidia. 


ACROGENS. 

face  of  the  frond  is  seen  by  a  low  magnifying  power  to 
be  divided  into  diamond-shaped  spaces,  containing  an 
opening  in  each.  On  making  a  thin  section,  as  in  Fig.  43, 


FIG.  43. — A.  Portion  of  frond  of  Marchantia  polymorpha  seen  from  above,  a.  a.  Loz- 
enge-shaped divisions,  b.  b.  Stomata  seen  in  the  center  of  the  lozenges,  c.  c.  Greenish 
bands  separating  the  lozenges.  B.  Vertical  section  of  the  frond,  showing  a.  a.  the  dense 
layer  of  cellular  tissue  forming  the  floor  of  the  cavity  d.  d.  b.  b.  Cuticular  layer,  forming 
its  roof.  c.  c.  Its  walls,  f.f.  Loose  cells  in  its  interior,  g.  Stoma  divided  perpendicu- 
larly, h.  Rings  of  cells  lorming  its  wall.  z".  Cells  forming  the  obturator  ring. 

each  of  these  stomata  will  be  seen  to  form  a  sort  of 
shaft,  or  chimney,  of  four  or  five  rings,  or  courses,  of 
cells,  the  lowest  ring  regulating  the  aperture  into  the 
leaf-grottoes  below. 

The  spores  of  Marchantia  are  attached  to  elaters,  or 
spirally-coiled  elastic  fibers,  whose  extension  scatters  the 
spores. 

3.  The  EQUISETACE^:,  or  Horsetails,  are  found  in 
most  parts  of  the  world,  save  Australia  and  New  Zea- 
land. They  generally  grow  in  wet  places,  sending  up 
shoots  from  a  creeping  stem,  or  rhizome.  The  cuticle  is 
remarkable  for  the  great  quantity  of  silica  contained  in 
it.  The  particles  of  this  mineral,  each  having  a  double 
axis  of  refraction,  are  arranged  in  rows  parallel  to  the 
axis,  and  are  beautiful  objects  under  the  microscope, 

with  polarized  light.     The  abundance  of  silica  has  led 
10* 


THE  SCIENCE  OF  LIFE. 


to  some  of  these  plants  being  used  as  natural  files  for 

polishing  various  articles. 

The   shoots  are  jointed,   each   articulation    having  a 

toothed  membrane- 
ous sheath,  and  hav- 
ing whorls  of  branch- 
es and  branchlets. 
The  fructification  is 
in  the  form  of  termi- 
nal cones,  with  scales 
bearing  spore-cases, 
and  opening  by  a 

FIG.  44.— a.  Equisetam   arvense.     o-  Equisetum  syl- 

vaticum.  c.  Section  of  the  spike,  d.  A  sporange.  e.  A  longitudinal  fisSUTC. 
spore  with  its  elaters  coiled. 

Each  of  the  spores 

has  a  pair  of  spiral  filaments,  with  clubbed  ends,  and 
attached  by  their  center,  so  as  to  look  like  four  stamens. 
(Fig.  44.) 

4.  FERNS  in  tropical  countries  are  sometimes  rivals  of 
the  most  beautiful  Palms,  having  trunks  varying  from 
two  or  three  to  sixty  or  eighty  feet  in  height,  formed  of 
the  consolidated  bases  of  the  fronds.  In  these  Tree- 
ferns  the  fronds  are  either  repeated  in  whorls,  or  they 
form  a  tuft  at  the  summit,  constituting  in  the  latter  case 
a  collection  of  whorls  with  suppressed  internodes.  In 
the  ordinary  ferns,  or  brakes,  of  temperate  climes,  the 
stem  is  an  underground  one,  or  rhizome,  and  the  dispo- 
sition of  the  fronds  is  seldom  observed. 

The  epidermis  of  the  stem  is  of  a  brownish  hue,  and 
the  general  cellular  structure,  or  parenchyma,  consists  of 
many-sided  nucleated  cells,  containing  chlorophyll  and 
starch  granules.  There  are  also  vessels  (annular,  spiral, 


ACROGENS.  115 

and  scalariform,  or  ladder-like)  and  fibrous  or  woody 
tissue,  forming  together  the  sclerenchyma,  or  harder  tis- 
sues. (Chap.  IV,  Sees.  6  to  10.) 

In  Fig.  45  the  acrogenous  growth  of  a  fern  is  illus- 
trated, together  with  the  metamorphosis  of  the  terminal 


FIG.  45.— Diagram,  showing  the  mode  of  growth  in  the  stem  of  a  Fern.  A.  B.  C. 
Stems  of  ferns  showing  successive  stages  of  growth,  a.  a.  a.  Terminal  cells,  the  latter 
just  after  being  produced  by  division,  b.  A  cell  which  will  give  rise  to  an  internode. 
c.  Shows  a  ring  or  cluster  of  cells  giving  rise  to  a  node.  d.  Epidermal  cells,  e.  Parenchyma. 
/".  Sclerenchyma.  g.  Scalariform  vessels,  h-  Spiral  vessels,  k.  An  appendage,  originating 
at  the  node.  d.  e.f.  g.  and  h.  all  arise  from  the  multiplication  and  metamorphosis  of  the 
"growing"  cells. 

cell  into  the  various  tissues.  In  flowering  plants  the 
terminal  cell  of  the  leaf-bud  becomes  barren,  and  the 
enlargement  of  the  leaf  depends  on  the  multiplica- 
tion and  growth  of  cells  nearer  the  base ;  but  in  the 
fern  the  leaf-bud  grows  as  the  stem  does,  so  that  the 
peduncle  is  first  formed,  then  the  embryo  leaf,  then  the 
pinnules,  etc. 

Underneath  the  frond  of  a  fern  we  may  sometimes  see 
little  brown  patches.  Each  patch  is  a  sorus,  (sometimes 
covered  by  a  membrane  called  an  indusium^]  and  the 
little  brown  bodies  constituting  it  are  sporangia,  or 
spore-cases,  which  have  been  developed  from  epidermal 
cells.  An  elastic  ring  (annulus)  surrounds  each  sporan- 
gium, and  assists  in  opening  it.  The  growth  of  these 


ii6  THE  SCIENCE  OF  LIFE. 

minute  spores  may  be  observed  by  sowing  them  on  a 
saucerful  of  fine  mold,  covering  with  a  bell-glass  or  tum- 
bler, and  keeping  it  moist,  warm,  and  shaded.  A  green 
film  will  spread  over  the  soil,  which  can  be  taken  up, 
from  time  to  time,  on  the  point  of  a  knife  for  microscopic 
examination.  The  little  spore  swells  and  bursts,  and 
throws  out  a  rootlet  which  gets  its  nourishment  from  the 
soil.  Then  a  number  of  delicate  cells  are  formed  from 
the  mother-cell  in  the  spore,  making  a  little  green  scale, 
(the  prothalliu m,)  which  throws  out  rootlets  on  its  under 
side.  This  prothallium  produces  two  kinds  of  cells,  one 
set  called  antheridia,  which  contain  spiral  filaments  which 
escape  to  enter  the  others,  called  archegonia,  or  germ- 
cells,  from  which  the  future  fern  is  reproduced.  (Fig.  46.) 

The  fossil  remains  of  Ferns  in  the  various  strata  of 
the  earth's  crust  are  very  numerous,  especially  in  the 
Coal  measures.  These  deposits  exhibit  the  remains  of 
many  species  now  extinct.  Immense  tree-ferns  and  gi- 
gantic Lycopodiaceae  (Club-mosses)  flourished  in  an  at- 
mosphere charged  with  moisture  and  carbonic  acid  gas, 
which,  by  plant  assimilation  and  liberation  of  oxygen,  is 
thought  to  have  been  purified  and  prepared  for  the  use 
of  successive  tribes  of  animals  and  of  man. 

5.  MOSSES  are  minute  and  lowly  plants,  but  they  are 
by  no  means  insignificant.  There  are  about  ten  thou- 
sand species,  some  of  which  are  not  over  a  hundredth 
part  of  an  inch  in  height,  while  others  are  several  inches 
high.  Mosses  have  a  distinct  axis  of  growth,  and  the 
delicate  leaves  are  arranged  with  great  regularity.  The 
stem  shows  some  indication  of  the  separation  of  a  cor- 
tical, or  bark-like  portion,  from  the  medullary,  or  pith- 


ACROGENS. 


117 


like,  by  the  intervention  of  a  circle  of  bundles  of  elon- 
gated cells,  from  which  prolongations  pass  into  the  leaves, 
so  as  to  afford  them  a  sort  of  midrib. 


FlG.  46. — Ferns  and  their  parts,  a.  Fronds  and  root-stalk,  b.  Frond,  showing  the 
spore-cases,  c.  Exterior  and  interior  of  seed-vessel,  d.  Fronds,  gradually  unfolding,  e.  A 
Theca,  or  spore-case,  before  opening,  f.  A  Theca,  or  spore-case,  discharging  its  spores. 
g.  Prothallus  of  its  natural  size.  h.  Lower  surface  of  prothallus,  much  enlarged,  showing 
the  organs  whose  reciprocal  action  determines  the  development  of  the  fern.  i.  Various 
forms  of  one  of  these  organs  when  in  movement.  j\  Inclosed  vesicle,  in  which  the  devel- 
opment of  the  fern  commences. 

The  root-fibers  are  long  tubular  cells,  quite  transpa- 
rent, within  which  the  circulation  of  the  bioplasm  may 
be  seen.  Dr.  Hicks  has  observed  portions  of  the  inclosed 
bioplasm  detached,  and  having  amceboid  motions. 


ii8  THE  SCIENCE  OF  LIFE. 

The  stems  of  Mosses  usually  terminate  in  filaments, 
or  foot-stalks,  supporting  an  urn-shaped  vessel  closed  by 
a  lid,  (operculum!)  which  is  covered  by  a  cap,  or  hood, 
(calyptra?)  Under  the  operculum,  the  edge  of  the  urn  is 
a  beautiful  toothed  fringe,  (the  peristome!)  and  within  the 


FIG.  47. --Structure  of  Mosses.  A.  Plant  of  Funaria  hygrometrica,  showing,  f.  the 
leaves  ;  u.  the  urns  supported  upon  the  setae,  or  footstalks,  j,  closed  by  the  operculum, 
0,  and  covered  by  the  calyptra,  c.  B.  Urns  of  Encalyptra  vulgaris^  one  of  them  closed 
and  covered  with  the  calyptra,  the  other  open.  u.  u.  The  urns.  o.  o.  The  opercula.  c.  Ca- 
lyptra. p.  Peristome.  s.  s.  Setae.  C.  Longitudinal  section  of  very  young  urn  of  Splach- 
num.  a.  Solid  tissue  forming  the  lower  part  of  the  capsule,  c.  Columella.  /.  Loculus, 
or  space  around  it  for  the  development  of  the  spores,  e.  Epidermic  layer  of  cells,  thick- 
ened at  the  top  to  form  the  operculum,  o.  p.  Two  intermediate  layers,  from  which  the 
peristome  will  be  formed,  s.  Inner  layer  of  cells  forming  the  wall  of  the  loculus. 

urn,  or  spore-capsule,   (sporangium^)   are   double-coated 
spores.     (Fig.  47.) 

In  developing  into  new  plants,  the  outer  coat  of  the 
spore  bursts  and  the  inner  wall  protrudes.  New  cells 
grow  from  the  extremity,  forming  a  filament,  whose  cells 
at  certain  points  multiply  by  subdivision,  so  as  to  form 
rounded  clusters,  like  the  prothallus  of  Ferns,  or  the  pro- 


ACROGENSVv       '  I IQ 

embryo  of  Chara,  from  each  of  which  an  independent 
plant  may  arise. 

The  urn,  or  capsule,  is  not  the  real  fructification  of  a 
moss,  but  its  product,  since  Mosses,  like  Liverworts,  etc., 
possess  both  antheridia  and  pistillidia,  although  they  are 
often  inconspicuous.  They  are  found  either  together, 
or  on  different  parts  of  the  same  plant,  or  on  different 
plants.  They  are  usually  situated  at  the  bases  of  the 
leaves,  close  to  the  axis.  The  antheridia  are  globular 
or  elongated  capsules  containing  sperm-cells,  each  of 
which  produces  a  moving  antherozoid,  which  escapes  at 
the  summit  of  the  capsule.  Hair-like  filaments  (para- 
physes)  around  the  antheridia  are  considered  to  be  ster- 
ile or  undeveloped  antheridia.  The  archegonia  are  like 
those  of  the  Hepaticeae,  and  when  fertilized  the  embryo- 
cell  develops  by  cell-division  into  a  conical  body  ele- 
vated upon  a  stalk.  This  tears  the  walls  of  the  flask- 
shaped  archegonium  by  a  circular  fissure,  carrying  the 
upper  part  as  the  calyptra,  or  hood  of  the  "  urn,"  while 
the  lower  part  remains  as  a  sort  of  collar  around  the 
stalk. 

6.  The  characteristics  of  the  type  of  Acrogens  are  the 
growth  of  cells  at  the  summit  only ;  the  appearance  of  a 
distinct  cortical  portion,  or  epiderm,  and  of  vascular  and 
fibrous  tissue  ;  and  a  sort  of  alternation  of  generations  in 
the  provision  of  a  prothallus,  so  that  plants  of  this  type 
may  not  improperly  be  designated  Prothallus  plants,  as 
the  higher  types  are  sometimes  known  as  Monocotyled- 
onous,  or  Dicotyledonous  plants. 

7.  As  an  illustration  of  the   reflections  natural  to  a 
well-regulated  mind  from  the  study  of  natural  objects, 


120  THE  SCIENCE  OF  LIFE. 

oven  of  minute  and  apparently  insignificant  Acrogens, 
an  incident  in  the  life  of  Mungo  Park  is  appropriate. 
This  enterprising  traveler,  during  one  of  his  journeys 
into  the  interior  of  Africa,  was  robbed  and  stripped  by 
banditti.  When  the  robbers  had  left  him,  he  says :  "  I 
sat  for  some  time  looking  around  me  with  amazement 
and  terror.  Whichever  way  I  turned,  nothing  appeared 
but  danger  and  difficulty.  I  found  myself  in  the  midst 
of  a  vast  wilderness,  in  the  depth  of  the  rainy  season, 
naked  and  alone,  surrounded  by  savage  animals,  and  men 
still  more  savage.  I  was  five  hundred  miles  from  any 
European  settlement.  All  these  circumstances  crowded 
at  once  upon  my  recollection,  and  I  confess  that  my 
spirits  began  to  fail  me.  I  considered  my  fate  as  cer- 
tain, and  that  I  had  no  alternative  but  to  lie  down  and 
perish.  The  influence  of  religion,  however,  aided  and 
supported  me.  I  reflected  that  no  human  prudence  or 
foresight  could  possibly  have  averted  my  present  suffer- 
ings. I  was  indeed  a  stranger  in  a  strange  land,  yet  I 
was  still  under  the  protecting  care  of  that  Providence 
who  has  condescended  to  call  himself  the  stranger's 
friend.  At  that  moment,  painful  as  my  reflections  were, 
the  extraordinary  beauty  of  a  small  moss  irresistibly 
caught  my  eye,  (I  mention  this  to  show  from  what 
trifling  circumstances  the  mind  will  sometimes  derive 
consolation,)  and,  though  the  whole  plant  was  not  larger 
than  the  top  of  one  of  my  fingers,  I  could  not  contem- 
plate the  delicate  conformation  of  its  root,  leaves,  and 
fruit  without  admiration.  Can  that  Being  (thought  I) 
who  planted,  watered,  and  brought  to  perfection,  in  this 
obscure  part  of  the  world,  a  thing  which  appears  of  so 


ACROGENS.  121 

small  importance,  look  with  unconcern  upon  the  situa- 
tion and  sufferings  of  creatures  formed  after  his  own 
image?  Surely  not.  Reflections  like  these  would  not 
allow  me  to  despair.  I  started  up ;  and,  disregarding 
both  hunger  and  fatigue,  traveled  forward,  assured  that 
relief  was  at  hand,  and  was  not  disappointed."  Such 
views  of  the  universe  and  of  its  Creator  infuse  strength 
into  the  human  soul,  and  give  a  vigor  to  human  charac- 
ter which  is  impossible  otherwise.  For  the  good-order- 
ing of  human  life  they  are  infinitely  above  all  Monistic 
speculations  and  theories  of  Evolution,  which  belittle 
or  lose  sight  of  the  individual  in  a  romantic  sentiment 
respecting  primordial  and  progressive  development  of 
all. 

11 


122  THE  SCIENCE  OF  LIFE. 


CHAPTER  IX. 

ENDOGENS. 

What  time  this  world's  great  workmaister  did  cast 
To  make  all  things  such  as  we  now  behold, 
It  seems  that  He  before  His  eyes  had  plast 
A  goodly  patterne,  to  whose  perfect  mould 
"Tie  fashioned  them  as  comely  as  he  could, 
That  now  so  fair  and  seemly  they  appear 
As  naught  may  be  amended  anywhere. 

— SPENSER. 

I.  ENDOGENOUS  plants  have  no  separable  bark,  nor 
distinct  concentric  circles  in  the  stem.  Their  fibro- 
vascular  bundles,  consisting  of  spiral  and  porous  vessels 
and  woody  fibers,  descend  from  the  leaves  downward, 
converging  at  first  toward  the  center,  but  afterward  di- 
verging outward  until  they  reach  the  roots,  or  attach 
themselves  to  the  hardened  tissue  of  the  outer  or  corti- 
cal layer,  corresponding  to  the  bark  in  Exogens,  but 
harder  than  the  rest  of  the  stem,  and  inseparable  from 
it.  It  used  to  be  thought  that  the  woody  portion  was 
added  to  the  center,  and  pushed  the  first-formed  fibers 
toward  the  circumference;  hence  the  term  Endogenous, 
(endon,  within,  and  gennao,  to  produce.)  In  strict  scien- 
tific accuracy  the  term  only  applies  to  the  fibers  at  the 
early  part  of  their  course,  since  in  the  latter  part  they 
become  blended  in  the  cortical  layer,  forming  a  tough 
net-work.  The  center  of  the  stem  when  young  is  filled 
with  cells  which  sometimes  disappear,  except  at  the 
nodes,  leaving  the  stem  hollow,  as  in  Grasses. 


ENDOGENS.  123 

The  embryo  of  Endogens  has  but  a  single  cotyledon, 
or  seed-lobe,  on  which  account  they  are  often  termed 
Monocotyledons.  Acrogens  have  no  seed-lobe,  but  cel- 
lular spores,  and  are  called  acotyledons,  (from  the  Greek 
a,  privative,  and  kotyledon,  something  hollow,)  while  Ex- 
ogens  have  two  seed-lobes,  and  are  dicotyledons. 

The  veins  in  the  leaves  of  Endogens   are  generally 
parallel,  or  straight,  (Fig.  48,)  and  do  not 
form  a  net-work,  and  the  parts  of  the  flower 
are  arranged  in  sets  of  threes,  or  of  some 
multiple  of  three. 

2.  Exceptions  to  the  parallel  venation  of 
leaves  in  Endogens  have  been  placed  by 
Lindley  in  a  class  by  themselves  —  the  Dic- 
tyogence,  (from  dictyon,  a  net,  and  gennao,  to 
produce  ;)  in  allusion  to  the  reticulation  of 
the  leaves.  They  comprise  the  Yam  tribe, 
(Dioscoreacece^)  the  Sarsaparilla  family,  (Smi- 
lacece^)  and  the  Trillium  family,  (  Trilliacece.} 
The  other  classes  or  sub-classes  are,  I.  Pe- 
taloidece,  or  Florida,  in  which  the  flowers 
consist  either  of  a  colored  perianth  (a  floral 
envelope)  or  of  scales  arranged  in  a  whorl. 
2.  Glumiferce,  in  which  the  flowers  have 
imbricated  bracts  or  scales,  called  glumes. 
This  includes  the  two  orders  of  grasses  and 
sedges.  The  Petaloidece  are  divided  into 
three  sections:  i.  Epigynce,  having  perfect 
flowers,  and  a  superior  perianth,  (ovary  infe- 

J  FIG.  48.-—  Endog- 

rior,)  as  Orchids,  Gingers,  Irids,  Amarylids,  enous  Leaf, 


T,  ing  parallel  vena- 

etc.  ;    2.  Hypogynce,  having  perfect  flowers  tion. 


124 


THE  SCIENCE  OF  LIFE. 


and  an  inferior  perianth,  (ovary  superior,)  as  Lilies, 
Rushes,  and  Palms ;  3.  Incomplete,  with  imperfect  flow- 
ers, without  a  proper  whorled  perianth,  as  Screw-pines 
and  Arums. 

3.  GRAMINE^:,  the  Grass  Family,  is  one  of  the  most 
important  orders  in  the  vegetable  kingdom,  whether  we 
regard  it  as  supplying  food  for  man  or  herbage  for  ani- 
mals. Grasses  are  found  in  all  quarters  of  the  globe; 
and  are  said  to  form  about  i-22d  part  of  known  plants. 
There  are  about  4,000  species,  and  their  structure  is  the 
most  simple  of  the  higher  forms  of  vegetation.  Their 
stems  form  protecting  sheaths  to  the  growing  shoots, 
and  have  alternate  leaves.  Their  flowers,  or  glumes, 
present  many  varieties,  producing  the  distinctive  char- 
acters of  families  or  tribes,  and  genera.  Among  the 
grasses  are  the  nutritious  cereal 
grains,  as  Wheat,  (Triticum,)  Oats, 
(Avena^)  Barley,  (Hordeum,)  Rye, 
(Secale,)  Rice,  (Oryza,}  Maize  or  In- 
dian Corn,  (Zea,)  etc.  Here,  also, 
are  found  various  pasture  grasses,  as 
Rye-grass,  (Lotmm,)  Timothy-grass, 
(P/tleum,)  Meadow-grass,  (Poa,)  etc. 
(Fig.  49.) 

The  cereal  grains  have  been  so 
generally  distributed  by  man  that 
all  traces  of  their  native  country  are 
lost.  They  seem  to  be  examples  of  permanent  varieties 
or  races  preserved  by  cultivation. 

The  grains,  or  seeds,  of  many  kinds  are  used  for  food, 
since  they  contain  a  large  amount  of  starch  and  gluten. 


FIG.  49.— Wheat,  Barley, 
Meadow-grass. 


ENDOGENS.  125 

Sugar  is  also  obtained  from  many  grasses,  as  the  Sugar- 
cane, (Saccharum  officinarum^)  Sweet  Sorghum,  (Sorghum 
saccJiaratum^)  etc. 

Grasses  contain  a  large  quantity  of  silicious  matter  in 
the  epidermis  of  their  stalks,  which  sometimes  accumu- 
lates in  the  joints,  as  the  Tabasheer  in  the  joints  of 
Bamboo,  (Bambusa?)  This  latter  is  a  tree-like  grass, 
sometimes  growing  fifty  or  sixty  feet  high.  It  is  applied 
to  an  almost  endless  variety  of  purposes.  The  Chinese 
use  it,  in  one  way  or  other,  for  nearly  every  thing  they 
require.  The  sails  of  their  ships,  as  well  as  their 
masts  and  rigging,  and  articles  of  furniture,  as  mats, 
screens,  chairs,  tables,  bedsteads,  and  bedding,  are  all 
made  out  of  the  Bamboo,  which  is  cultivated  with  great 
care. 

The  stems  of  some  grasses  run  under-ground,  and  are 
useful  in  consolidating  the  sand  of  the  sea-shore.  This 
property  renders  some  grasses  (as  Triticum  repeus)  diffi- 
cult to  exterminate. 

4.  SEDGES,  (Cyperacece^  are  grass-like  herbs,  with 
angular  stems  and  narrow,  tapering  leaves  wrapping 
found  the  stem,  but  without  the  slitting  sheath.  Their 
flowers  are  borne  on  bracts,  or  scales,  united  in  an  im- 
bricated manner  so  as  to  form  a  spike.  In  Lapland  they 
equal  the  grasses  in  number,  but  the  proportion  de- 
creases toward  the  equator.  Few  plants  of  this  family 
are  attractive  to  the  eye,  but  many  of  them  are  useful. 
The  creeping  stems  of  Carex  arenaria  bind  the  shifting 
sands  on  the  shores  of  Brittany  and  Holland  into  a  wind- 
defying  mass.  The  Papyrus  antiquorum  of  the  Nile  (the 

Bulrush  of  Scripture)  belongs  to  this  family.      It   for- 
11* 


126 


THE  SCIENCE  OF  LIFE. 


merly  furnished   the  world   with  paper,  besides   being 
used  for  making  boats,  ropes,  etc.    (Fig.  50.) 


,: 


FIG.  50. — The  Papyrus  of  the  Nile. 


FIG.  51. — Cocoa-nut  Tree,  (Cocos  nuctfera,) 
and  Plantain,  (Musa  Paradisiacal) 


5.    Linnaeus,   the   great   Botanist,   called    Grasses  the 
plebeians,    and    PALMS    the    princes,    of    the   vegetable 


ENDOGENS.  127 

world.  The  latter  are  for  the  most  part  trees  of  gigan- 
tic growth,  often  reaching  dimensions  unknown  among 
other  plants.  They  are  used  for  supplying  food  and  for 
forming  habitations.  The  fruit  of  some  is  edible,  while 
that  of  others  is  hard.  Many  supply  oil,  wax,  starchy 
matter,  and  sugar,  which  is  fermented  to  form  an  intoxi- 
cating beverage.  Their  fibers  make  ropes,  and  the  re- 
ticulum  about  their  leaves  is  sometimes  manufactured 
into  brushes. 

The  Date  palm,  (Phoenix  dactylifera,)  which  supplies 
food  to  so  many  of  the  inhabitants  of  Arabia  and  Africa, 
is  considered  to  be  the  Palm  of  the  Bible.  The  Cocoa- 
nut  palm  (Cocos  nuciferd)  is  one  of  the  most  useful, 
supplying  the  South  Sea  Islander  with  food,  clothing, 
houses,  utensils,  ropes,  oil,  sugar,  wine,  and  Palm  cab- 
bage from  the  terminal  bud,  etc.  (Fig.  51.) 

Sago  and  other  starchy  matter  is  obtained  by  bruising 
and  washing  the  cellular  tissue  of  many  Palms,  espe- 
cially Sagus  Rumphiiy  S.  lavis  and  5.  genuina. 

6.  The  BANANA  family  (Musacecz)  contains  plants 
which  furnish  a  large  supply  of  nutritious  fruit,  while 
their  leaves  afford  valuable  fibers.  The  best  known  spe- 
cies are  Musa  paradisiaca,  or  Plantain,  and  M.  sapientum, 
or  Banana,  (Fig.  52 ;)  the  former  a  denizen  of  the  Old 
World,  and  the  latter  of  the  New.  The  specific  name 
of  the  first  originated  in  a  notion  of  some  of  the  old 
botanists  that  it  was  the  forbidden  fruit  of  Eden.  A 
quaint  writer  remarks  that  it  is  not  likely  that  a  plant  so 
useful  should  have  been  the  forbidden  fruit.  The  Ba- 
nana supplies  the  inhabitants  of  the  tropical  islands  with 
wholesome  and  abundant  food,  pleasant  drink,  valuable 


128  THE  SCIENCE  OF  LIFE. 

medicine,  materials  for  clothing,  baskets,  mats,  and  with 
almost  all  other  necessaries  of  their  simple  life.     Musa 


FIG.  52. — Banana,  (Musa  sapientum.) 

textilis  supplies  a  flax-like  fiber,  from  which  some  of  the 
finest  Indian  muslins  are  made. 

7.  The  ARROW-ROOT  family,  (Marantacea^  the  PINE- 
APPLE family,  (Bromeliacece^)  and  the  GINGER  family. 
(Zingiberacece^)  contain  many  useful  species  of  Endogens. 
Here  also  are  classed  many  of  the  showy  flowers  of  our 
gardens  and  hot-houses.  The  IRIS  family,  (Iridacece^) 
containing  the  Iris,  Gladiolus,  and  Crocus,  etc. ;  the 
singular  aquatic  plants  of  the  Hydrocharidaceae,  as  Hy- 
drocharis  and  Valisneria ;  and  the  AMARYLLIS  family, 
(Amaryllidacece^)  embracing  the  Daffodil,  Amaryllis,  and 


ENDOGENS. 


129 


Agave,  are  of  this  class.  The  last-named  plant  is  some- 
times called  the  American  Aloe,  (Agave  Americana,) 
and,  according  to  gardening  fable,  only  blooms  once  in 
a  hundred  years,  hence  called  Century  plant.  Its  large, 
hard,  spinous  leaves  grow  slowly  for  years,  when  sudden- 
ly, in  the  course  of  a  single  season,  a  stem  shoots  up  forty 
or  fifty  feet  in  height,  bearing  a  crest  of  flowers.  In 
Peru  and  Mexico  an  intoxicating  beverage  called  pulque 
is  made  from  the  sap. 

8.  The  ORCHID  family  (Orchidacece]  exhibit  the  great- 


FIG.  53.—  Orchids,  (Orchidacete.) 


est  variety  of  forms  and  brilliancy  of  color  among  all  the 
vegetable  tribes.     The  flowers  often  resemble  insects,  as 


130 


THE  SCIENCE  OF  LIFE. 


butterflies,  moths,  flies,  and  spiders  ;  or  birds,  as  doves 
and  eagles  ;  or  reptiles,  as  snakes,  lizards,  and  frogs. 
(Fig.  53.)  Their  spots  and  colors  give  sometimes  the 
appearance  of  leopard  or  tiger  skins.  These  resemblances 

are  indicated  in  their 
generic  and  s  p  e  c  i  fi  c 
names.  Some  parts  of 
the  petals  of  these  flow- 
ers display  peculiar  irri- 
tability, for  the  purpose 
of  scattering  the  fertiliz- 
ing pollen.  As  the  vis- 
its of  insects  are  often 
subsidiary  to  the  fertili- 
zation of  Orchids,  they 
have  attracted  much  at- 
tention from  naturalists. 
They  abound  chiefly  in 
moist  tropical  climates. 

9.  The  LlLY  family 
(Liliacece)  includes  many 
showy  garden  flowers, 
as  Tulips,  Lilies,  Dog- 
tooth-violets, and  Tube- 
roses. (Fig.  54.)  It  is 
divided  into  several 
tribes,  as  the  Onion,  or 
Squill  tribe,  the  Aspho- 
del tribe,  the  Lily-of-the- 
valley  tribe,  the  Aloes 
FIG.  54.— The  white  L:iy,  (Luium  aidvm.)  tribe,  and  the  Asparagus 


ENDOGENS.  131 

tribe.  In  the  latter  tribe  are  placed  the  Dragon-trees, 
the  most  gigantic  of  the  order.  There  is  one  in  the 
Island  of  Teneriffe  which  is  described  as  seventy  feet 
high  and  forty-six  feet  in  circumference  at  the  base. 
The  flowers  are  small.  From  some  species  of  Dragon- 
tree  the  Sandwich  Islanders  prepare  an  intoxicating 
liquor  called  ava. 

The  inspissated  juice  of  several  species  of  Aloe  is  used 
in  medicine  as  a  cathartic,  and  the  bulb  of  the  Squill  is 
imported  from  the  coasts  of  the  Mediterranean,  and  is 
valued  for  its  diuretic,  expectorant,  and  other  properties. 

A  species  of  Onion  called  Camass  is  used  by  the  In^ 
dians  of  Oregon  as  food. 

Textile  fibers  are  procured  from  New  Zealand  flax 
(Phormium)  and  from  the  Yucca,  or  Adam's  needle. 

10.  The  SCREW-PINE  family  (Pandanus)  contains  sev- 
eral species  which  exhibit  a  semblance  of 

instinct  in  the  development  of  aerial  roots 
at  different  distances  on  the  stem,  by  which 
their  life  is  prolonged.  Their  leaves  are 
arranged  in  a  spiral,  hence  the  name, 
Screw-pine. 

11.  The    ARUM    family    contains    the 
Cuckoo-pint  tribe,  the  Bulrush  tribe,  (Fig. 
55,)  the  Sweet-flag  tribe,  and  the   Duck- 
weed  tribe.     In   the    Duckweed  (Lemnd) 
we  see  at  a  casual  glance  nothing  but  a 

green  scale  floating  on  the  water,  which  is  FlG>55'~~] 
in  reality  a  compound  of  both  root  and  stem.  A  careful 
observation  in  summer  may  lead  to  the  discovery  of  mi- 
nute straw-colored  anthers  on  the  edges  of  the  plants, 


132  THE  SCIENCE  OF  LIFE. 

and  near  these  a  narrow  slit,  which,  on  being  enlarged, 
will  show  the  simple  flower,  like  a  membraneous  bag, 
and  containing  two  stamens  and  one  ovary,  with  its  style 
and  simple  stigma. 

IT.  Protophytes,  Thallogens,  and  Acrogens  have  been 
classed  together  in  the  artificial  system  of  Linnaeus  as 
Cryptogamia,  (from  cryptus,  hidden,  and  gamos,  nuptials,) 
in  allusion  to  the  inconspicuous  character  of  their  repro- 
ductive organs  ;  while  Endogens  and  Exogens  are  called 
PJianerogamia,  (phaneros,  visible,  and  gamos,  nuptials,) 
since  they  have  perceptible  reproductive  organs  formed 
of  stamens  and  pistils.  To  these  essential  parts  we  fre- 
quently find  two  envelopes  added,  the  calyx  and  corolla. 
These  parts  make  up  the  flower,  and  the  Phanerogamia 
are  not  infrequently  known  as  flowering  plants. 

The  flower  consists  of  whorled  leaves  placed  on  an 
axis,  the  internodes  of  which  are  not  developed.  There 
are  usually  four  of  these  whorls.  The  outer  whorl  is  the 
calyx,  the  next  the  corolla,  the  third  the  stamens,  and 
the  innermost  the  pistil.  In  Exogens  the  calyx  is  usu- 
ally green  and  the  corolla  colored,  but  in  Endogens  both 
frequently  display  rich  coloring,  and  are  apt  to  be  con- 
founded, so  that  the  term  perianth  is  usually  applied  to 
the  flowers  of  Endogens,  whether  colored  or  otherwise, 
(peri,  around  ;  anthos,  flower.) 

The  parts  of  the  calyx,  when  separate,  are  called  se- 
pals, and  the  leaves  of  the  corolla  petals.  Stamens  have 
two  parts,  the  filament,  or  stalk,  and  the  anther,  or 
broader  portion,  corresponding  to  the  folded  blade  of 
the  leaf,  and  containing  fertilizing  grains  called  pollen. 
The  pistil  is  also  made  up  of  two  parts,  the  ovary,  con- 


ENDOGENS. 


FIG.  56.— A.  Sectional  view  of  the  flower,  showing  the  vertical  disposition  of  the  whorls. 
(i.  Sepal  of  calyx,  b.  Petal  of  corolla,  c.  Filament  of  stamen,  d.  Anther  cf  stamen. 
f.  Ovary  of  pistil,  f.  Style  of  pistil,  g.  Stigma  of  pistil.  B.  Plan  of  the  typical  flower  of 
an  exogenous  plant,  showing  the  horizontal  disposition  of  its  parts,  a.  Sepal,  b.  Petal. 
c,  c.  Stamens  in  two  distinct  whorls,  d.  Carpel  or  ovary,  inclosing  an  ovule,  attached  by 
its  funiculus.  C.  Various  parts  of  the  clove,  a.  Flower  of  the  clove  or  pink.  b.  Vertical 
and  middle  section  of  the  flower,  c.  Flower  reduced  to  its  male  and  female  portions ;  the 
stamens  are  six  in  number — four  large,  (in  pairs,)  and  two  small.  <£  One  of  the  petals. 
e.  Horizontal  section  of  the  ovary,  or  seed-vessel;  showing  the  insertion  of  the  ovules. 
/".  Fruit  at  the  moment  of  expansion,  g.  Seed,  with  its  funiculus.  h.  Vertical  section  of 
the  seed  and  its  embryonic  contents,  i.  The  embryo  alone,  k.  Horizontal  section  of  the 
seed  and  its  embryonic  contents. 

1*5 


134  THE  SCIENCE  OF  LIFE. 

taining  ovules  or  young  seeds,  and  the  stigma,  a  cellular 
secreting  body  for  the  reception  of  the  pollen-grains. 
This  is  sometimes  sessile,  or  resting  on  the  ovary,  and 
sometimes  elevated  on  a  stalk,  or  style.  Like  the  other 
whorls,  the  pistil  is  made  up  of  one  or  more  modified 
leaves,  named  carpels.  (Fig.  56.) 

Some  flowers  have  no  stamens,  and  are  called  female 
flowers ;  others  have  no  pistil,  and  are  male  flowers  ; 
but  both  stamens  and  pistils  are  always  present,  either 
on  the  same  plant  or  on  different  plants.  Some  flowers 
have  neither  calyx,  corolla,  nor  stamens  ;  others,  neither 
calyx,  corolla,  nor  pistil.  If  they  have  no  corolla  they 
are  incomplete,  and  if  corolla  and  calyx  are  both  absent 
they  are  naked. 

The  general  axis  of  inflorescence  is  called  rachis ;  the 
stalk  supporting  a  flower  or  a  cluster  of  flowers  is  a  pe- 
duncle, and,  if  small  branches  are  given  off  by  it,  they  are 
called  pedicels.  Sometimes  the  floral  axis  is  shortened, 
and  is  flat,  convex,  or  concave,  bearing  numerous  flow- 
ers, as  in  the  Daisy.  It  is  then  called  a  receptacle. 

Flowers  are  always  the  termination  of  an  axis,  branch, 
or  bough,  and  the  order  governing  their  arrangement  is 
a  repetition  of  that  which  governs  the  ramification  of  the 
plant. 

Bracts,  or  floral  leaves,  are  leaves  from  which  the  floral 
axis,  or  the  individual  flowers,  arise.  Sometimes  they 
are  colored  and  may  be  mistaken  for  parts  of  the  corolla, 
and  at  other  times  they  are  undeveloped.  Bracts  are 
generally  deciduous,  but  occasionally  persist,  and  even 
form  part  of  the  fruit,  as  in  the  cones  of  Firs  and  the 
fruit  of  the  Pine-apple.  In  catkins  (or  imperfect  unisex 


ENDOGENS.  135 

ual  sessile  flowers  on  a  spike,  as  in  the  Willow  or  Hazel) 
the  bracts  are  called  scales.  A  whorl  of  bracts  is  an  in- 
volucre. These  are  sometimes  adherent,  as  in  the  cup 
of  the  Acorn.  A  sheathing  bract  inclosing  one  or  more 
flowers  is  a  spathe.  This  is  common  among  Endogens, 
as  in  Calla,  Arum,  and  the  Palms.  In  Grasses  the  outer 
scales  are  considered  as  sterile  bracts,  and  have  received 
the  name  of  glumes. 

The  various  modes  of  inflorescence  is  a  subject  of 
profound  study  with  botanists,  but  its  details  are  too 
extensive  for  the  design  of  the  present  work.  As  stated 
in  Chap.  IV,  Sec.  n,  the  parts  of  the  flower,  as  regards 
their  development,  structure,  and  arrangement,  may  all 
be  referred  to  the  leaf  as  a  type.  They  begin  like  leaves 
in  cellular  projections,  in  which  fibre-vascular  tissue  is 
ultimately  formed ;  they  are  arranged  in  a  more  or  less 
spiral  manner,  and  they  are  often  partially  or  entirely 
changed  into  leaves.  These  facts  confirm  Goethe's  doc- 
trine that  all  the  parts  of  the  flower  are  altered  leaves. 

12.  In  the  type  of  Endogens  we  meet  with  a  great 
variety  of  flowers,  some  perfectly  organized,  as  the  Lily, 
and  others,  as  the  Duckweed  and  Bulrushes,  quite  in- 
complete. Yet  even  in  the  more  lowly  forms  we  meet 
with  abundant  examples  of  the  care  of  a  beneficent 
Providence  accomplishing  intelligent  designs  by  various 
ways,  but  all  indicative  of  Divine  wisdom.  In  the 
Branched  Bur-reed  (Sparganium  ramosum)  the  branches 
bear  yellow  balls  of  staminate,  or  barren  flowers,  and 
green  pistillate,  or  fertile  florets.  "  What  happens  in 
this  case,"  says  Dr.  Lindley,  "  occurs  also  in  all  instances 
in  which  the  stamens  are  separated  from  the  pistils  in 


136  SCIENCE  OF  LIFE. 

different  flowers  on  the  same  plant ;  we  invariably  find 
that  the  stamens  are  placed  on  the  uppermost  parts  of 
the  branch  above  the  pistils,  an  arrangement  which  is 
no  doubt  provided  to  facilitate  the  scattering  of  their 
pollen  upon  the  stigmas.  If  they  were  placed  below 
the  pistils  it  would  be  much  more  difficult  for  the  pol- 
len to  reach  the  stigma,  and  consequently,  the  great 
end  of  the  creation  of  the  stamens  would  be  almost 
frustrated.  We  find,  however,  that  every  thing  is  fore- 
seen and  provided  for  by  Providence,  with  the  same 
care  in  these  little  plants  as  in  the  most  exalted  and 
perfect  of  the  works  of  nature ;  and  that  even  so  appa- 
rently useless  and  insignificant  a  weed  as  the  Bur-reed 
contains  the  most  convincing  evidence  of  the  worthless- 
ness  of  the  opinions  of  those  who,  denying  the  existence 
of  the  Deity,  would  have  the  world  believe  that  living 
things  are  the  mere  result  of  a  fortuitous  concourse  of 
atoms,  attracting  and  repelling  each  other  with  different 
degrees  of  force."*  The  recent  elaborate  observations 
of  Darwin,  Sir  J.  Lubbock,  and  others,  upon  the  fertil- 
ization of  plants,  as  the  Orchids,  by  the  visits  of  insects, 
although  sought  to  be  explained  by  the  principle  of 
11  unconscious  natural  selection,"  finds  a  more  ready  and 
satisfactory  explanation  in  the  case  of  an  ever-present 
Providence,  since  if  the  colors,  and  honey,  and  structure 
of  the  flowers  are  "  all  arranged  with  reference  to  the 
visits  of  insects,"  f  the  structure  and  habits  of  insects 
are  equally  adapted  to  the  fertilization  of  the  flowers. 
From  the  design  we  infer  a  Designer. 

*"  Ladies'  Botany,"  by  Dr.  J.  Lindley. 

f  Lubbock's  "  Wild  Flowers  in  Relation  to  Insects." 


EXOGENS.  137 


CHAPTER  X. 

EXOGENS. 

In  all  places,  then,  and  in  all  seasons, 

Flowers  expand  their  light  and  soul-like  wings, 
Teaching  us,  by  most  persuasive  reasons, 

How  akin  they  are  to  human  things. 
And  with  childlike,  credulous  affection, 

We  behold  their  tender  buds  expand, 
Emblems  of  our  own  great  resurrection, 

Emblems  of  the  bright  and  better  land. 

— LONGFELLOW. 

i.  THE  term  Exogen  (from  exo,  outward,  and  gennao, 
to  produce)  is  applied  to  those  plants  which  produce 
woody  and  vascular  layers  toward  the  circumference. 
It  is  the  largest  class,  or  type,  in  the  vegetable  kingdom, 
including  about  7,000  genera  and  70,000  species  of  flow- 
ering plants. 

External  to  the  woody  layers,  and  between  them  and 
the  bark,  is  a  layer  of  semifluid  mucilaginous  matter 
called  Cambium.  Its  cells  are  exceedingly  delicate. 
New  cells  are  continually  being  added,  on  the  inner  side 
of  the  Cambium  layer,  to  the  thickness  of  the  wood, 
and  on  the  outer  side  of  it,  to  the  thickness  of  the  bark, 
increasing  the  diameter  of  the  axis  of  the  plant. 

At  the  apex  of  the  stem,  and  at  that  of  the  root,  the 
Cambium  layer  is  continuous  with  the  cells  which  retain 
the  power  of  dividing  in  these  localities. 

The  general  appearance  of  the  axis  of  an  exogenous 

plant  is  that  of  a  double  cone;  one  cone  representing 
12* 


138 


THE  SCIENCE  OF  LIFE. 


the  stem,  the  other  the  root  ;  the  growing  part  of  both 

being  bathed  in  the  cambium  fluid. 

In  the  growing  stem  the 
terminal  cells  (a.  Fig.  57, 
A)  multiply  and  enlarge, 
while  they  furnish  new 
cells  to  the  cambium  layer. 
In  the  root,  however,  the 
multiplying  cells  are  not 
quite  at  the  extremity.  A 
sort  of  cap  is  formed  by 
the  growing  cells,  (pileor- 
hiza^)  and  receives  addi- 
tions to  its  interior,  which 
push  out  the  layers  exter- 
nal to  them.  (Fig.  57,  B, 
C.)  Thus  efficient  protec- 
tion is  afforded  to  the  new- 

FIG.  57.  —  A.  Mode  of  growth  in  stem.  B.  In  -  , 

root.     A.  a.  Growing  cells  in  stem,   which      ly-tormed  tlSSUC. 
multiply  by  fission,    b.  Cambium,  elaborated 
by  growing   cells.     B.  a.  Growing   cells   in 

root.    b.  Cells  produced  by  growing   cells.      Qf   the   tisSUCS    of   3. 
c.  Cap,  (pileorhiza.)     C.  Root  of  duckweed, 

(magnified.)  «.  Growing  point,    b.  Root-    ing  plant  may  be  seen  in 

sheath,   c.  Cap.    d.  Root.  . 

Fig.  58.     Air  passages  are 

both  intercellular  and  vascular,  the  latter  in  Exogens 
being  dotted  ducts  and  spiral  vessels.  The  bark  con- 
tains elongated  liber  or  bast  cells,  but  there  are  no  sca- 
lariform  vessels  as  in  Acrogens.  The  chlorophyll  (Chap. 
VI,  Sec.  2)  is  found  chiefly  in  the  cells  immediately  un- 
der the  epidermis.  See  also  Figs.  15  and  16.  The  roots 
are  supplied  with  water  containing  carbonic  acid,  air, 
and  oxygen,  in  addition  to  the  minerals  and  decompos- 


crf-rif^r^  1   a  rra  n  cr^m  (*n  r 


EXOGENS.  139 

ing  organic  matter  (or  humus)  contained   in  the   soil. 

Some  plants  grow  without  attachment  to  the  soil,  deriv- 

ing  all    their   nutriment    from 

the    air,    and    are    called   Epi- 

phytes, (epi,    upon;   phyton,    a 

plant,)    from    being    generally 

found   on    trees.      They   differ 

from   true   parasites,  since  the 

latter  prolong  their  tissues  into 

other    plants,    and    prey   upon 

them.     The  Orchids  may  illus- 

trate the  first,  and  the  Dodder 

and  Mistletoe  the  latter  kind. 

The  only  structure  capable  of 
effecting  the  chemical  changes 

FIG.  58.—  Diagrammatic  Section  of  a 

necessary   tO    plant    nutrition    is    Flowering  Plant,  showing  the  different 
.  tissues.     A.  Ascending  axis.    B.  De- 

the   Chlorophyll,   Which    IS    mOSt    scending  axis.    s.  Surface  of  soil.   c.  c. 
.  .  .       ,..         •.  -I  Appendages,  d.  Growing  point  of  stem. 

abundant  in  the  leaves;  hence  ,.Epidermis.  ././.  stomata:  g.  Layer 
the  materials  which  supply  food  —  ? 


must    be    carried    up    to    the  '•  m-  «•  pit^  sPiral  vessel>  and  dotted 

duct  —  all  air  passages,    r.  r.   Roots. 

leaves.         The      aSCent      Of     fluid    t.  Growing  point  of  roots.   w.Cap,  (pil- 

eorhiza.) 

from   the    root   to   the    leaves 

takes  place  by  means  of  two  distinct  forces  —  a  pushing 
force,  caused  by  absorption  by  the  extremities  of  the 
rootlets,  and  endosmose  (Chap.  IV,  Sec.  3)  from  cell  to 
cell;  and  a  pulling  force,  produced  by  evaporation  from 
the  surface  of  the  leaves. 

The  appendages  of  the  root  are  the  rootlets,  and  of 
the  stem,  the  leaves.  Leaves  are  developed  from  the 
nodes,  and  the  internodes  (Chap.  VIII,  Sec.  2)  become 
shorter  toward  the  summit  of  the  stem,  which  ends  in 


140  THE  SCIENCE  OF  LIFE. 

a  terminal  bud.  Buds  are  also  developed  in  the  axils  of 
the  leaves,  and  some  of  them  grow  into  branches,  which 
repeat  the  characters  of  the  stem  ;  but  others,  when  the 
plant  is  fully  developed,  grow  into  stalks  which  support 
the  flowers. 

In  Chap.  IX,  Sec.  II,  will  be  found  a  general  descrip- 
tion of  the  flower,  and  in  Chap.  IV,  Sec.  n,  an  account 
of  the  tissues  forming  the  leaf.  The  arrangement  of 
leaves  and  branches  is  also  a  subject  of  biological  in- 
terest. The  mode  in  which  branches  come  off  from 
the  nodes  gives  rise  to  various  forms  of  trees,  such  as 
pyramidal,  spreading,  or  weeping.  In  the  Italian  Pop- 
lar and  Cypress  the  branches  are  erect,  forming  acute 
angles  with  the  upper  part  of  the  stem ;  in  the  Oak  and 
Cedar  they  are  spreading ;  while  in  the  Weeping  Wil- 
low and  Birch  they  are  pendulous  from  their  flexibil- 
ity. Leaves  also  are  placed  in  a  fixed  order  for  every 
species  of  plant,  and  this  order  may  be  expressed  by  an 
arithmetical  formula.  The  arrangement  of  the  leaves 
on  the  axis  is  called  phy  Hot  axis,  (phyllon,  a  leaf;  taxis, 
order.)  Each  node  of  the  axis  may  give  rise  to  a  leaf, 
but  sometimes  several  nodes  are  approximated  nearly 
together,  and  then  several  leaves  may  be  produced  at 
the  same  height  on  the  stem.  When  two  leaves  are  at 
the  same  level,  one  on  each  side  of  the  stem,  they  art- 
called  opposite ;  when  a  circle  of  leaves  is  thus  produced 
it  is  called  a  verticil,  or  whorl.  When  a  single  leaf  is 
produced  at  a  node,  and  the  nodes  are  separated,  the 
leaves  are  alternate.  The  relative  position  of  alternate 
leaves  varies  in  different  plants,  but  is  tolerably  uniform 
in  each  species.  In  a  regularly-formed  branch  covered 


EXOGENS.  141 

with  leaves,  if  a  thread  is  passed  from  one  to  the  other, 
turning  always  in  the  same  direction,  a  spiral  is  de- 
scribed, and  a  certain  number  of  leaves  and  of  complete 
turns  occur  before  reaching  the  leaf  directly  above  that 
which  began  the  series.  This  may  be  expressed  by  a 
fraction,  the  numerator  of  which  indicates  the  number 
of  turns,  and  the  denominator  the  number  of  leaves  in 
the  spiral  cycle.  In  the  Peach  and  Plum-tree  the  cycle 
embraces  five  leaves,  and  the  spiral  goes  twice  around 
the  branch.  This  is  expressed  by  the  formula  f .  In  the 
Alder  three  leaves  constitute  the  cycle,  and  the  spiral 
has  only  a  single  turn  on  the  stem ;  the  disposition  of 
its  leaves  is  represented  by  the  fraction  £. 

In  Exogenous  plants  the  leaves  are  reticulated,  and 
usually  articulated  to  the  stem.  The  flowers  are  formed 
upon  a  quinary  or  quaternary  type ;  that  is,  their  parts 
are  in  sets  of  fives  or  fours,  instead  of  sets  of  threes,  as 
Endogens.  The  embryo  has  two  opposite  cotyledons, 
or  seed-lobes,  which  gives  the  term  Dicotyledonous  to 
the  type. 

2.  According  to  the  natural  system  of  De  Candolle, 
w-hich  is  usually  followed,  Exogens  are  subdivided  as 
follows : 

i.)  THALAMIFLOR^:,  (Thalamus,  receptacle,  and  flos, 
flower.)  Calyx  and  corolla  present ;  petals  distinct,  in- 
serted into  the  receptacle ;  stamens  hypogynous,  or 
growing  from  below  the  ovary,  as  Ranunculus,  Magno- 
lia, Poppy,  Violet,  Geranium,  etc. 

2.)  CALYCIFLORA.  A  calyx  and  corolla  present,  the 
petals  distinct,  but  the  stamens  are  perigynous,  or  at- 
tached to  the  calyx  ;  as  Rhamnus,  the  Leguminose  fam- 


142  THE  SCIENCE  OF  LIFE. 

ily,  the  Rose  family,  the  Syringa,  the  Passion-flower, 
Cactus,  etc. 

3.)  COROLLIFLOR^E.  Calyx  and  corolla  present ;  pet- 
als united,  bearing  the  stamens  ;  as  the  Honeysuckle, 
Madder,  Teazel,  Composite  family,  Heaths,  etc. 

4.  MONOCHLAMYDE^:,  (Monos,  one  ;  chlamus,  a  cloak, 
or  covering.)  Sometimes  called  INCOMPLET/E.  Corolla 
wanting ;  a  calyx  or  simple  perianth  present.  (Even 
this  sometimes  absent.)  It  is  divided  into  two  sec- 
tions : 

A.  Angiospermce.      Seeds   contained   in   an   ovary,   as 
Amaranth,    Phytolacca,    Buckwheat,    Laurel,    Begonia, 
Nettle,  Fig,  and  the  Catkin-bearing  family. 

B.  Gymnospermce.     Seeds  naked.     Their  woody  tissue 
is  marked  by  disks,  (Chap.  IV.  Sec.  9 ;)  as  the  Coniferae 
and  Cycas  family. 

3.  Among  the  INCOMPLETE  Exogens,  belonging  to 
the  section  of  Gymnosperms,  or  naked-seeded  Exogens, 
are  found  the  Cycas  family,  (CYCADACEvE,)  which  greatly 
resemble  the  Palms  and  Tree-ferns,  and  the  Cone-bear- 
ing family,  (CONIFERS,)  divided  into  the  Fir  and  Spruce 
tribe,  (Abietinea^)  the  Cypress  tribe,  (Cupressineaf)  the 
Yew  tribe,  (Taxinece,  and  the  Joint-fir  tribe,  (Gnetacece^ 

The  Coniferous  plants  are  noble  trees  or  evergreen 
shrubs,  and  furnish  valuable  timber  and  other  important 
products,  as  turpentine,  pitch,  and  resin.  The  Pine  (Fig. 
59)  is  one  of  the  most  perfect  trees  of  the  forest,  con- 
sidered in  respect  to  its  beauty  and  uses.  "  Its  charac- 
ter and  glory,"  writes  Mr.  Ruskin,  "  consist  in  its  right 
doing  of  its  hard  duty,  and  forward  climbing  into  those 
spots  of  forlorn  hope  where  it  alone  can  bear  witness  of 


EXOGENS. 


143 


the  kindness  of  the  Spirit  that  cutteth  out  rivers  among 
the  rocks,  as  it  covers  the  valleys  with  corn  ;  and  there, 
in  its  vanward  place,  and  only  there,  where  nothing  is 
withdrawn  for  it,  nor  hurt 
by  it,   and   where    nothing 
can  take  part  of  its  honor, 
nor  usurp  its  throne,  are  its 
strength,  and  fairness,  and 
price,  and   goodness  in  the 
sight  of  God  to  be  truly  es- 
timated." 

4.  Among  the  ANGIO- 
SPERM  EXOGENS,  or  those 
of  the  Incomplete  class 
whose  seeds  are  inclosed 
in  an  ovary.  The  principal 
families  are  the  Marvel  of 
Peru,  the  Amaranth,  the 
Phytolacca,  the  Buckwheat, 
the  Begonia,  the  Laurel,  the 
Nutmeg,  the  Oleaster,  the 
Daphne,  the  Sandalwood, 
the  Birthwort,  the  Pitcher- 
plant,  the  Rhizogen,  the 
Spurge,  the  Nettle,  the 
Pepper,  the  Walnut,  and 
the  Catkin-bearing  families. 

To  the  Buckwheat  family 

(POLY GONACEyE)  belong  the  FlG>  59--Pines,  (Pznus  Sylvestris) 

Buckwheat,  (Fagopyrum  esculentum^  the  Sorrel,  (Rumex 
Acetosa,)  and  Rhubarb,  (Rheum  palmatum)     In  the  Lau- 


144 


THE  SCIENCE  OF  LIFE. 


rel  family  are  the  Laurel,  Bay,  Camphor,  Sassafras,  and 
Cinnamon  trees. 

The  Pitcher-plants  (Nepenthes)  are  among  the  curiosi- 
ties of  the  vegetable  world,  on  account  of  the  pitcher 

formed  at  the  end  of  the 
leaf.  This  is  furnished 
with  a  lid,  and  contains 
a  limpid  fluid  secreted 
by  glands  in  the  cavity, 

I  K-Wk^    ^^  and  in  sufficient  quanti- 

ty to  drown  flies  and 
other  insects  which  fall 
into  it.  (Fig.  60.)  Since 
the  publication  of  Mr. 
Darwin's  "  Insectivorous 
Plants/'  these  secreting 
leaves  (together  with 
those  of  several  other 
species)  have  attracted 
much  attention,  as  in  all 
probability  there  is  in 
these  arrangements  provision  for  a  true  digestion,  as  in 
the  case  of  animals. 

The  Euphorbiacecz,  or  Spurge  family,  contains  many 
trees,  shrubs,  and  herbs,  abounding  in  acrid  milky  juice, 
which  is  generally  poisonous.  Siphonia  elastica  is  one  of 
the  plants  which  supplies  caoutchouc,  or  India-rubber. 
The  seeds  of  Croton  Tiglium  affords  Croton  oil,  and  those 
of  Ricinus  communis  (or  Palma  Christi)  furnish  Castor- 
oil.  In  the  root  of  Janipha  Manihot  there  is  much 
starchy  matter  mingled  with  a  volatile  poison.  The  lat- 


FIG.  60.— Pitcher-plant,  (Nepenthes  distil- 
latorza-.) 


EXOGENS.  145 

ter  is  removed  by  heat  or  washing,  and  the  starch  is 
used  as  Cassava  bread.  Tapioca  and  Brazilian  Arrow- 
root are  said  to  be  procured  in  this  way. 

In  the  NETTLE  family  are  about  six  hundred  species, 
including  the  common  Nettle,  Hemp,  Hop,  Elm,  Fig, 
Mulberry,  Bread-fruit,  the  Banyan,  (Ficus  indica^)  etc. 

The  Catkin-bearing  family  (AMENTACE^)  is  the  larg- 
est and  most  important  of  this  order,  since  it  contains 
all  the  most  important  timber  trees.  (Fig.  61.)  The 


Alder,  Birch,  Willow,  Poplar,  Oak,  Chestnut,  Hornbeam, 
and  Plane  are  here  brought  together  because  of  the  simi- 
larity of  their  fructification.  They  produce  flowers  of  one 

sex  only,  the  males  of  which  are  in  catkins,  in  which  the 
13 


,46  THE  SCIENCE  OF  LIFE. 

flowers  have  neither  calyx  nor  corolla,  but  merely  a  sin- 
gle scale.  Their  bark  has  an  astringent  quality  from  the 
presence  of  tannin,  and  some,  as  the  Willow,  yield  a 
valuable  tonic  febrifuge,  (Salicin^)  The  fruit  of  many 
species  contains  starchy  matter,  rendering  it  edible  by 
man  or  animals,  as  the  acorns  of  oak,  mast  of  birch,  nuts 
of  the  hazel,  etc. 

5.  In  the  order  COROLLIFLORvE,  or  Exogens  having 
the  petals  united,  and  bearing  the  stamens,  are  to  be 
found  the  Mistletoe,  the  Honeysuckle,  Peruvian  bark, 
Valerian,  Teazel,  Harebell,  Lobelia,  Heath,  Cranberry, 
Ebony,  Holly,  Jasmine,  Olive,  Asclepias,  Dog-bane, 
Gentian,  Trumpet-flower,  Phlox,  Convolvulus,  Borage, 
Nightshade,  Figwort,  Labiate,  Vervain,  Acanthus,  Prim- 
rose, and  Composite  families. 

The  Honeysuckle  family  (CAPRIFOLIACE^E)  is  divided 
into  the  true  Honeysuckle  tribe  (Lonicerece)  and  the  El- 
der tribe,  (Sambucecz?) 

The  Peruvian  Bark  family  (RUBIACE^E)  contains,  in 
addition  to  the  Peruvian  bark  of  commerce,  (Cinchona?) 
the  Ipecacuanha,  (Ccphaelis  Ipecacuanha^)  the  Coffee-tree, 
(Coffca  arabica^)  and  the  Madder,  (Rubia  tinctorial) 

The  Heaths  (ERICACEAE)  contain  many  beautiful  and 
showy  plants,  as  the  Rhododendrons,  Azaleas,  and  Kal- 
mias.  The  Partridge-berry,  (Gaultheria  procumbeus^  the 
Bear-berry,  (Arctostaphylos  Uva-Ursi,)  and  the  Chima- 
philla,  (Pyrola  innbcllata^)  are  sometimes  used  in  medicine. 

In  the  Olive  family  (OLEACE^:)  is  placed  the  Olive, 
Lilac  or  Syringa,  and  the  Ash,  (Fraxinus  excelsior?) 

The  Gentians  (GENTIANACE^E)  are  mostly  dwarf  her 
baceous  plants,  with  deep  blue  flowers. 


EXOGENS.  147 

The  CONVOLVULACE^E,  or  Bind-weed  family,  are  twin- 
ing plants  with  showy  flowers,  except  the  tribe  of  Dod- 
ders, (Cuscutecz,)  which  are  leafless  parasites.  Here  we 
find  the  Jalap,  and  Scammony,  and  Sweet-Potato,  (Bata- 
tas, edulis^) 

The  Nightshade  family  (SoLANACE^)  contains  the 
Potato,  (Solanum  tuberosum^)  the  Deadly  Nightshade, 
(Atropa  Belladonna^  the  Henbane,  (Hyoscyamus  niger} 
the  Thorn-apple,  (Datura  Stramonium^)  Tobacco,  (Nice- 
tiana  Tabacum^)  Cayenne-pepper,  (Capsicum  annium,}  the 
Tomato,  (Lycopersicum  esculentum^)  etc. 

The  LABIATE  are  characterized  by  two  long  and  two 
short  stamens,  four  little  nuts  or  naked  seeds,  and  ir- 
regular corollas.  The  plants  are  generally  fragrant  and 
aromatic,  and  none  of  them  are  injurious.  Many  are 
used  in  medicine  as  carminatives.  Mint,  Lavender, 
Sage,  Savory,  and  Balm,  are  examples  of  the  family. 
From  Thyme  a  sort  of  camphor  has  been  procured  called 
Thymol,  which  has  similar  antiseptic  properties  to  Car- 
bolic acid,  but  with  pleasant  odor. 

The  family  COMPOSITE  is  a  very  extensive  one.  The 
florets  are  arranged  in  involucrated  heads,  and  the  an- 
thers cohere  into  a  cylinder.  It  is  subdivided  into  three 
sections:  I.  Cynarocephalce,  (from  cynara,  the  Artichoke,) 
having  all  the  flowers  tubular;  the  involucre,  hard,  con- 
ical, and  often  spiny,  as  the  Thistle,  Burdock,  etc. 
2.  Corymbiferce,  (corymbus,  a  comb,  and  fero,  to  bear,) 
having  tubular  florets  in  the  disk  (center)  and  ligulate  in 
circumference,  (or  ray;)  involucre  hemispherical,  leafy,  or 
scaly,  rarely  spiny,  as  Feverfew,  Wormwood,  Tansy,  Ar- 
nica, and  Sunflower.  3.  Cichoracece,  (cichorium,  succory,/ 


148  THE  SCIENCE  OF  LIFE. 

having  the  florets  all  ligulate,  as  Chicory,  Dandelion,  and 
Lettuce.  The  Daisies,  Asters,  Chrysanthemums,  and 
Dahlias  of  the  gardens  are  all  composite  flowers. 

6.  In  the  subdivision  of  CALYCIFLORE^E  are  placed 
Exogens  which  have  a  calyx,  and  corolla  with  distinct 
petals,  and  whose  stamens  are  attached  to  the  calyx. 

In  the  Buckthorn  family  (RHAMNACE^:)  we  find  the 
genus  Rhamnus,  several  of  whose  species  yield  cathartic 
medicine,  and  Ceanothus,  or  Mountain  tea. 

The  Cashew-nut  family  (ANACARDIACE^:)  contains  the 
Cashew-nut,  (Pistacia  vera})  Rhus  Toxicodcndron,  or  Poi- 
son-oak, and  many  plants  which  furnish  varnishes,  as  the 
Japan  lacquer,  (Stagmaria  verniciflua^} 

A  number  of  fragrant  balsamic  resins,  including  myrrh, 
(Balsamodendron  Myrrha?)  are  obtained  from  plants  of 
the  Amyris  family,  (AMYRIDACE^E.) 

The  Pea  and  Bean  family  (LEGUMINOS^:)  is  very  ex- 
tensive, containing  more  than  four  hundred  and  fifty 
genera  and  six  thousand  five  hundred  species.  It  em- 
braces many  valuable  medicinal  plants,  as  those  yielding 
Senna,  Gum-arabic,  Tragacanth,  Catechu,  and  Kino; 
important  dyes,  as  Indigo  and  Logwood ;  valuable  tim- 
ber-trees, as  Locust-tree  and  Rosewood ;  and  plants  fur- 
nishing nutritious  food,  as  the  Bean  and  Pea.  This 
order  has  been  divided  into  three  sub-orders,  I.  Papilio- 
nazece ;  having  papilionaceous  flowers,  the  petals  imbri- 
cated in  aestivation,  and  the  upper  one  exterior.  The 
plants  of  this  section  often  have  beautiful  showy  flowers, 
as  Robinia,  Laburnum,  Lupinus,  etc.  The  various  kinds 
of  Clover,  Beans,  Peas,  and  Pulse  belong  to  it.  The 
Glycyrrhiza glabra,  or  plant  yielding  liquorice-root,  the 


&XOGENS.  149 

Myroxylon  peruiferum,  or  source  of  the  Balsam  of  Peru, 
and  many  other  plants  having  medicinal  qualities,  are 
found  here.  2.  Ccesalpinece.  Flowers  irregular,  but  not 
papilionaceous,  petals  spreading,  imbricated  in  aestiva- 
tion, upper  one  interior.  Here  we  find  the  place  of  sev- 
eral plants  used  in  medicine,  as  various  species  of  Cassia 
or  Senna,  the  Tamarind-tree,  and  the  Logwood,  (Hcema- 
toxylon?)  3.  Mimosece.  Flowers  regular,  petals  valvate 
(without  overlapping)  in  aestivation ;  as  the  different 
species  of  Acacia,  yielding  Gum  Arabic,  and  the  MimostB, 
or  Sensitive  plants. 

The  Rose  family  (ROSACE^)  is  also  a  very  large  one  be- 
longing to  the  Calyciflorece.  Its  sub-orders  are,  I.)  Chrys- 
obalancce,  petals  and  stamens  irregular,  ovary  stipitate, 
its  stalk  adhering  to  the  side  of  the  calyx,  style  basilar, 
fruit  a  i-2-celled  drupe,  (or  fleshy  fruit.)  2.)  Amyg- 
dalece,  tube  of  calyx  lined  with  a  disk,  styles  terminal, 
fruit  a  drupe.  3.)  Spiraea,  calyx-tube  herbaceous,  lined 
with  a  disk,  fruit  of  numerous  follicles,  seeds  apterous. 
4.)  Quillaiece,  flowers  unisexual,  calyx-tube  herbaceous, 
fruit  capsular,  seeds  winged  at  the  apex.  5.)  Sangui- 
sorbea,  petals  none,  tube  of  calyx  thickened  and  indu- 
rated, stamens  definite,  nut  solitary,  inclosed  in  the 
calycine  tube.  6.)  Potentillece,  calyx-tube  herbaceous, 
lined  with  a  disk  which  sometimes  becomes  fleshy,  fruit 
consisting  of  numerous  achaenia,  (small,  brittle,  seed-like 
fruit.)  7.)  Rosece,  calyx-tube  contracted  at  the  mouth, 
becoming  fleshy,  lined  with  a  disk,  and  covering  numer- 
ous hairy  achaenia.  8.)  Pomece,  tube  of  calyx  more  or 
less  globose,  ovary  fleshy  and  juicy,  lined  with  a  thin 

disk,  fruit  a  i-5-celled,  or  spuriously  lO-celled,  pomum. 
13* 


150  THE  SCIENCE  OF  LIFE. 

Many  of  the  plants  of  this  order  yield  edible  fruits,  as 
Raspberries,  Strawberries,  Plums,  Apples,  Pears,  Cher- 
ries, Peaches,  and  Apricots.  Plants  of  the  sub-order 
Amygdaleae  are  remarkable  for  the  presence  of  hydro- 
cyanic acid,  as  in  the  kernel  of  the  Almond,  (Amygdalns 
communis^  especially  the  bitter  Almond ;  the  leaves 
of  the  Peach,  (Amygdalus  persica,)  and  of  the  Cherry- 
laurel,  (Prunus  Laurocerasus.}  The  sub-order  Pomeae 
supplies  Apples,  Pears,  and  Quinces.  The  seeds  contain 
hydrocyanic  acid.  The  other  sub-orders  have  plants 
distinguished  by  astringent  and  tonic  properties,  as  the 
root  of  Potentilla  Tormentilla,  and  the  petals  of  Rosa 
gallica,  the  Red  Rose. 


FIG.  62. — A  Mangrove  Forest. 


EXOGENS.  151 

The  RHIZOPHORACE^E,  or  Mangrove  family,  is  named 
after  Rhizophora  Mangle,  the  Mangrove,  which  forms 
thickets  at  the  muddy  mouths  of  rivers  in  tropical 
countries,  and  sends  out  adventitious  roots  which  often 
raise  up  the  main  trunk,  and  give  the  tree  the  appear- 
ance of  being  supported  on  stalks.  (Fig.  62.)  The  fruit 
is  sweet  and  edible. 

The  Myrtle  family  (MYRTACE^E)  contains  trees  or 
shrubs  which  are  usually  natives  of  warm  countries. 
Some  of  the  genera  are  peculiar  to  Australia,  as  the 
Eucalyptus,  or  Blue  Gum-tree,  which  is  being  planted 
extensively  in  California.  It  is  a  rapid  grower,  and 
promises  to  be  serviceable  as  a  forest  tree.  It  contains 
a  medicinal  balsamic  resin.  The  Pimento,  (Myrtus  Pi- 
menta,)  the  Pomegranate,  (Punica  Granatum,)  and  vari- 
ous species  of  edible  Guavas  and  Rose-apples  belong  to 
this  order.  . 

The  Evening  Primrose  (CEnothera)  and  the  FucJisia 
belong  to  the  order  ONAGRACE^E,  or  the  Evening  Prim- 
rose family. 

The  Cucumber  family  (CUGURBlTACEyE)  contains  many 
plants  that  are  drastic  purgatives,  and  others  whose  fruits 
under  cultivation  are  edible,  as  the  Melon  and  the  Colo- 
cynth,  both  species  of  the  same  genus,  (Cucumis.) 

The  Passion-flowers  (PASSIFLO  RACEME)  received  their 
name  from  a  fancied  resemblance  to  the  scenes  at  Cal- 
vary. The  superstitious  monks  saw  in  the  five  anthers 
a  resemblance  to  the  wounds  of  Christ ;  in  the  triple 
style,  the  three  nails  on  the  cross ;  in  the  central  pillar, 
the  cross  itself;  and  in  the  filamentous  processes,  the 
rays  of  light  round  the  Saviour,  or  the  crown  of  thorns. 


152  THE  SCIENCE  OF  LIFE. 

The  PORTULACACE^:,  or  Purslane  family,  are  chiefly 
herbaceous  plants,  found  in  dry,  barren  situations,  or  on 
the  sea-shore.  Some  of  them  have  tuberous  roots  which 
have  been  proposed  as  substitutes  for  the  potato,  as 
Claytonia  tuber  osa,  and  Melloca  tuber osa.  The  first  is  a 
Siberian  plant,  the  other  a  native  of  Peru. 

The  Cactus  family  (CACTACE^E)  contains  many  succu- 
lent plants,  destitute,  for  the  most  part,  of  leaves,  the 
place  of  which  is  supplied  by  fleshy  stems  of  grotesque 
figures.  Some  are  angular,  and  grow  to  a  height  of 


FIG.  63. — A  Group  of  Cactacese. 

thirty  feet;  others  are  roundish,  covered  with  stiff  spines, 
and  not  over  a  few  inches  high.  Their  flowers  are  often 
large  and  beautiful,  varying  from  pure  white  to  rich 
scarlet,  or  purple.  Some  are  night-flowering,  as  the 
Cereus  grandiflorus.  In  Mexico  and  Southern  Califor- 
nia there  are  a  large  number  of  species,  some  of  which 
are  of  gigantic  size.  (Fig.  63.) 


EXOGENS.  153 

The  Gooseberry  and  Currant  family,  (GROSSULARIA- 
CE.E,)  the  Saxifrage  family,  (SAXIFRAGACE.E,)  the  Witch- 
hazel  family,  (HAMAMELIDACE^E,)  are  all  of  this  section 
of  Exogens,  with  many  others.  The  Umbelliferous  fam- 
ily (UMBELLIFERE^E)  are  characterized  by  the  radiating 
or  umbrella-like  arrangement  of  the  florets.  The  prop- 
erties of  the  plants  of  this  family  are  various.  Some 
yield  articles  of  diet,  as  the  Parsnip,  (Pastinaca  sativa^) 
Carrot,  (Daucus  Carota,}  and  Parsley,  (Petroselinum 
sativum.)  Others  yield  milky  juices,  which  dry  into  a 
fetid  gum-resin,  as  the  Ferula  Assafcetida,  yielding  Assa- 
fcetida,  and  Dorema  Ammoniacum,  which  produces  Am- 
moniae.  Others  again  supply  a  carminative  and  aro- 
matic oil,  as  Caraway-seeds  (Carum  Carui)  and  Fennel, 
(F&niculum  dulce.)  Some  species  are  quite  poisonous, 
as  the  Conium  maculatum,  or  Hemlock,  which  contains 
a  volatile  alkaline  poison,  called  Conia. 

7.  In  the  sub-class,  or  order  THALAMIFLOR^E,  the 
stamens  are  inserted  under  the  pistil  into  the  thalamus, 
or  receptacle.  The  petals,  also,  are  inserted  into  the 
receptacle.  In  some  cases  the  petals  are  abortive,  and 
it  becomes  hard  to  determine  whether  the  plant  belongs 
to  this  division  or  to  Monochlamydeae. 

The  RANUNCULACE.E,  or  Crowfoot  family,  is  charac- 
terized chiefly  by  having  several  distinct  carpels,  above 
numerous  stamens.  The  plants  are  generally  narcotic 
acid  poisons.  The  Ranunculus,  Anemone,  Larkspur, 
Aconite,  and  Peony  are  examples. 

The  leaves  of  Aconitum  Napellus,  or  Monkshood,  are 
used  in  medicine,  as  well  as  the  rhizome  of  Podophyllum 
peltatum,  or  May  Apple. 


154  THE  SCIENCE  OF  LIFE. 

The  Poppy  family  (PAPAVERACE^E)  differs  from  the  last 
in  having  the  carpels  united  into  an  undivided  ovary, 

and  in  having  milky  or 
colored  juice.  Opium  is 
the  dried  juice  of  Papavcr 
somniferum,  (Fig.  64,)  or 
Poppy,  and  its  varieties. 
The  Celandine  (Chelidoni- 
um  majus]  yields  an  or- 
ange-colored juice,  which 
is  said  to  be  acrid.  In  the 
leaf  of  this  plant  may  be 
seen  under  the  microscope 
the  movement  of  the  sap 
in  the  laticiferous  vessels. 
Sanguinaria  canadensis,  or 
Blood-root,  has  emetic  and 
cathartic  properties.  The 
yellow  California  Poppy 
(Eschscholtzid)  is  remark- 
able for  the  two  sepals  of 
its  calyx  adhering  at  the 
edge,  and  separating  at 
the  base  by  the  growth  of 

the  ^Wcr     SO  as  tO  form   3. 


FIG.  64.-TheOpium-Pla(/'«A,Wr  somni- 

ferum-  sort  of  calyptra,  or  hood, 

over  the  unexpanded  petals,  resembling  the  extinguish- 
er of  a  candle. 

MAGNOLlACEyE,  the  Magnolia  family,  contains  the  well- 
known  Magnolias,  remarkable  for  large  odoriferous  flow- 
ers, the  Swamp  Sassafras,  (M.  glauca^)  whose  bark  is  used 


EXOGENS.  155 

as  a  substitute  for  the  Peruvian  bark,  and  the  Lirioden- 
dron  tulipifera,  or  Tulip-tree,  etc. 

The  Side-saddle  family  (SARRACENIACE.E)  contains 
the  genera  Sarracenia  and  Darlingtonia,  which  (like  Ne- 
penthes) are  characterized  by  a  pitcher-like  append- 
age to  the  leaf,  containing  a  fluid  secretion,  supposed 
to  have  the  power  of  digesting  insects  which  fall 
into  it. 

CRUCIFER^E,  the  Cruciferous,  or  Cress-wort  family, 
known  so  readily  by  their  four  cruciate  petals,  contains 
a  large  number  of  plants,  none  of  which  are  poisonous, 
although  some  are  stimulant  and  even  acrid.  Most  of 
the  common  culinary  vegetables  belong  to  this  order,  as 
Cabbage,  Cauliflower,  Turnip,  Radish,  Cress,  and  Mus- 
tard. Many  garden  flowers  also  are  of  this  family,  as 
Wallflower  and  Alyssum. 

The  Violet  family,  (VlOLACE^,)  the  Mignonette  family, 
(RESEDACE^:,)  the  Berberry  family,  (BERBERIDACE^E,) 
the  Rock-Rose  family,  (ClSTACE^E,)  the  St.  John's-wort 
family,  (HYPERICACE^E,)  the  Vine  family,  (VlTACE^E,) 
the  Geranium,  or  Crane's-bill  family,  (GERANIACE^E,)  the 
Wood-sorrel  family,  (OXALIDACE^E,)  and  many  others, 
must  be  passed  by,  since  space  forbids  us  to  enlarge. 

The  Quassia  family  (SiMARUBACE^E)  is  noted  for  the 
bitter  and  tonic  principle  contained  in  the  wood  of  Quas- 
sia amara,  and  other  species. 

The  Rue  family  (RUTACE^E)  is  also  known  in  medi- 
cine, since  it  furnishes  Rue,  Buchu,  (Barosma  crenata^) 
and  other  agents. 

The  Flax  family  (LINAGE^:)  furnishes  the  well-known 
Flax,  (Linum  usitatissimum^  whose  inner  bark  yields 


I56 


THE  SCIENCE  OF  LIFE. 


linen    and    cambric.     The   seeds   are   mucilaginous  and 
oleaginous. 

The  Water-lily  family  (NYMPH^CE^E)  contains  plants 
with  showy  flowers.   (Fig.  65.)     Victoria  regina  is  one  of 


FIG.  65. — Common  Water  Lily,  (Nymphcea  alba.) 

the  largest  known,  the  white  and  rosy  flowers  being  four 
feet  in  diameter,  and  the  leaves  fifteen  feet  across,  ac- 
cording to  Schlieden. 

DROSERACE^:,  .the  Sundew  family,  is  remarkable  for 
its  insectivorous  properties.  The  Droseras  are  furnished 
with  glandular  hairs,  which  exhibit  drops  of  fluid  in  sun- 
shine, hence  the  name. 

Dioncea  muscipula,  Venus's  Fly-trap,  has  the  laminae  of 
the  leaves  in  two  halves,  each  furnished  with  three  irri- 
table hairs,  which,  on  being  touched,  cause  the  folding 
of  the  divisions  in  an  upward  direction. 

The  Chickweed  and  Pink  family  (CARYOPHYLLACE/E) 
contains  all  the  Carnations,  or  Pinks,  (Dianthus^)  Chick- 
weed,  (Stellaria  media,)  etc. 

The  Mallow  family  (MALVACE^)  contains  many  whole- 
some mucilaginous  plants.  The  Mallow,  (Malva^  the 
Hollyhock,  (Althcea  rvsea,)  the  Abutilon,  (A.  esculentum^} 
and  the  Cotton-plant,  (Gossypium^)  belong  here.  (Fig.  66.) 


EXOGENS. 


157 


The  produce  of  the  latter  plant  employs  the  labor  of  a 
million  and  a  half  of  people  in  England  alone,  and  fur- 
nishes clothing  to  hun- 
dreds of  millions. 

The  Tea  family  (TERN- 
STR^MIACE^E)  has  in  it 
the  beautiful  Camellias 
of  Japan,  and  the  plants 
which  furnish  tea,  (Thea- 
viridis  and  Bohca^  The 
use  of  the  leaves  of  these 
plants  is  immense,  no 
less  than  fifty-six  mill- 
ions of  pounds  being  im- 
ported into  Great  Britain 

in  a  single  year,  (1846.)  FlG-  66-The  Cotton-piant, 
The  bitter  principle  in  tea,  called  theine,  may  be  pro- 
cured by  adding  a  slight  excess  of  acetate  of  lead 
to  a  decoction  of  tea,  filtering  hot,  evaporating,  and 
subliming. 

The  Orange  family  (AURANTlACEyE)  contains  about  a 
hundred  species.  The  plants  contain  receptacles  of  vola- 
tile oil.  The  fruit  has  an  acid  or  subacid  pulp,  and  the 
wood  is  compact.  The  Orange,  Lemon,  Lime,  Citron, 
and  Shaddock  belong  here. 

AcERACEvE,  the  Maple  family,  contains  the  Maple  and 
Sycamore,  (Acer  pseudo-platanus^}  The  Sugar  Maple 
(A.  saccharinum)  yields  a  sap  from  which  sugar  is  manu- 
factured. 

The  Mahogany  family  (CEDREIACE^E)  contains  plants 

with  an  aromatic  fragrance.     Swietenia  Mahogoni  sup- 
14 


158  THE  SCIENCE  OF  LIFE. 

plies  the  well-known  mahogany  wood,  and  Chloroxylon 
Swietenia,  satin  wood. 

8.  In  the  rapid  sketch  we  have  made  of  the  vegetable 
kingdom,  we  have  omitted  the  minute  botanical  details 
characteristic  of  each  family,  and  have  only  given  the 
principal  differences  and  resemblances  of  types  and 
classes,  with  some  few  representative  forms  in  the  most 
important  families.  These  general  peculiarities  of  plants 
serve  in  a  great  degree  to  define  the  character  of  land- 
scape scenery  in  various  parts  of  the  world.  Gray  and 
withered  Lichens  clothe  the  barren  confines  of  vegeta- 
tion toward  the  snow-line  of  mountains  or  at  the  north, 
while  Mosses  form  a  silken  cushion  over  rock  and  soil 
with  their  delicate  leaflets. 

Grasses  are  characterized  by  their  sociability,  and  call 
forth  agreeable  sensations  by  their  soft  carpet  of  green 
and  pliant  leaves.  The  Sedges,  on  the  contrary,  with 
stiff  and  rugged  stems  and  leaves,  rejected  by  cattle, 
awaken  no  pleasing  associations.  In  tropical  climates, 
as  in  Hindustan,  the  tall  Bamboo  sometimes  overtops 
the  trees,  and  forms  a  meadow  above  the  forest.  There 
the  Plantain  stem  swells  with  sap,  the  leaves  expand  and 
are  split  by  the  wind,  and  the  great  flower-bunches  beam 
with  intense  color.  Between  the  reeds  and  the  banana 
plants  the  lilies  may  be  placed.  The  arrow-shaped 
leaves  of  the  Aroids,  with  strange  and  often  brightly- 
colored  spathes,  mark  the  transition  to  the  Orchids. 

The  stems  as  well  as  the  leaves  of  plants  often  give 
character  to  a  landscape,  as  in  the  Heaths — low,  branch- 
ing, dull-green  or  gray  shrubs,  whose  blossoms  scarcely 
obliterate  the  melancholy  impression  produced  where 


EXOGENS.  159 

they  abound.  The  arborescent  Heaths  (Casuarina]  form 
many  of  the  gloomy  woods  of  Australia.  Still  more 
striking  are  the  forms  of  the  thorny  Cactuses,  (Fig.  63,) 
consisting  merely  of  fleshy  stems  and  branches  of  singu- 
lar shapes.  The  Yuccas  of  Mexico,  the  great  African 
Aloes,  and  the  Grass-trees  of  Australia,  with  their  solid 
liliaceous  leaves,  of  a  dull  green,  afford  a  picture  of  im- 
movable repose.  The  stiff,  shining  leaves  of  Pandanus, 
or  Screw  Pine,  arranged  in  spiral  lines,  contrast  greatly 
in  the  Sandwich  Islands  with  the  finely  divided  leaves 
of  the  Fern,  spreading  in  graceful  elegance,  and  trem- 
bling in  the  breeze.  Between  these  two  extremes  is  the 
Palm-form,  which  gives  most  characteristic  beauty  to  the 
tropical  world.  Some  Palms  have  feathered  leaves, 
others  have  fan-leaves,  and  in  some  of  the  umbrella 
Palms  the  crown  consists  of  a  few  fans  elevated  on  long, 
slender  stalks.  In  all  the  inflorescence  breaks  from  the 
stem  below  the  origin  of  the  leaves,  and  the  sheath 
hangs  down,  often  several  feet  long.  The  shape  and 
color  of  the  fruit  varies  from  the  large  triangular  Cocoa- 
nut  to  the  berry  of  the  Date.  The  aerial  summits  of 
the  Palms,  projecting  like  a  colonnade  above  the  thicket, 
and  crowned  with  leaves,  give  them  an  air  of  beautiful 
majesty.  (Fig.  51.)  Deciduous,  or  Leafy  woods,  (Fig. 
61,)  with  their  branching  stems  and  broad  foliage,  form 
dense,  compact,  vegetable  masses,  characteristic  of  tem- 
perate climes.  Wand-like  forms,  with  narrow,  fluttering 
leaves,  often  covered  with  silvery  down  on  the  under 
side,  are  represented  by  the  Willow  and  Poplar,  and  in 
the  south  of  Europe  by  the  Olive.  The  Conifers,  or 
Needle-leaved  woods,  are  distinguished  by  their  narrow, 


160  THE  SCIENCE  OF  LIFE. 

dark-green  leaves  and  whorl-like  branches.  (Fig.  59.) 
In  the  tropical  or  equinoctial  regions  the  mass  of  leafy 
woods  is  marked  by  the  prevalence  of  the  Mallow-form, 
with  long-stalked  and  palmately-lobed  leaves.  The 
giant  Baobab,  the  barrel-like  trunk  of  the  Bombax,  and 
the  purple-blossomed  Hibiscus  bush  belong  to  this  class. 
The  Australian  Laurels  and  Myrtles  are  allied  to  the 
northern  Willows,  yet  their  rigid  leaves,  shining  as  if 
varnished,  or  covered  with  a  silvery  felt  which  mingles 
with  the  shining  green,  give  them  a  characteristic  phys- 
iognomy. 

Thus  even  a  general  observer  may  notice  variety 
enough  to  indicate  that  a  free  intelligence  has  arranged 
these  forms  to  minister  mental  enjoyment,  as  well  as  to 
supply  the  needs  of  intelligent  creatures.  Archbishop 
Trench  has  well  said  that  the  characters  of  nature  which 
every-where  meet  the  eye  "  are  not  a  common,  but  a  sa- 
cred writing — they  are  hieroglyphics  of  God." 


PROTOZOA.  161 


CHAPTER  XI. 

PROTOZOA. 

Since  all  bioplasm  possesses  certain  common  characters,  and  the  bio- 
plasm of  one  plant  or  animal  produces  formed  matter  of  a  very  different 
kind  from  that  resulting  from  another  portion  of  bioplasm,  we  must  ad- 
mit that  in  nature  there  are  different  kinds  of  bioplasm. — DR.  BEALE'S 
Bioplasm. 

I.  IN  studying  the  structure  of  the  Protozoa,  or  primi- 
tive animals,  we  seem  to  be  going  backward,  since  each 
is  composed  of  a  single  mass  of  bioplasm,  like  the  sim- 
plest vegetables,  or  Protophytes.  Although  similar  in 
structure,  the  Protozoa  and  the  Protophytes  are  biolog- 
ically distinct  in  function,  since  the  latter  generally  de- 
compose Carbonic  acid  under  the  influence  of  light,  and 
generate  Chlorophyll  and  albuminous  compounds  in  a 
manner  similar  to  the  leaf-cells  of  the  most  perfect 
plant,  while  the  Protozoa  ingest  and  digest  both  animal 
and  vegetable  food  as  effectively  as  the  most  complex 
animals. 

We  have  already  seen  (Chap.  II,  Sec.  7)  that  all  living 
matter,  or  bioplasm,  has  essentially  spontaneous  motion, 
nutrition,  growth,  and  reproduction.  We  cannot  con- 
ceive, therefore,  of  any  form  of  life,  either  vegetable  or 
animal,  without  these  characteristics.  The  simplest  and 
most  embryonic  structures  in  both  kingdoms  of  nature 
exhibit  these  functions.  Whether  spontaneous  motion 
is  proof  of  consciousness  and  will,  will  be  considered 

hereafter. 
H* 


162  THE  SCIENCE  OF  LIFE. 

2.  The  MONERA  of  Prof.  Haeckel,  if  the  group  shall  be 
accepted  by  naturalists,  will  include  the  simplest  proto- 
zoans, cr  those  in  which  the  entire  living  body  is  a  mere 
particle  of  bioplasm,  without  nucleus,   vacuole,  invest- 
ment, or  other  structure,  yet  capable  of  bioplasmic  mo- 
tions  and   other  functions.      Bathybius,    referred  to  in 
Chap.  IV,  Sec.  3,  was  supposed  to  be  of  this  class. 

3.  The  GREGARINID^:  are  parasitic.     Each  consists  01 
a  single  cell,  which  passes  through  changes  similar  in 
many  respects  to  Protophytes.     It  becomes  globular  and 
encysted  in  a  horny  envelope,  and  the  inclosed  bioplasm 
breaks  up  into  particles  which  become  "  pseudo-navicel- 
lae,"  or  forms  similar  to  the  Navicula  of  the  family  Dia- 
tomaceae.     It  is  not  unlikely  that  the  Gregarince  are  but 
phases  in  the  life-history  of  other  parasitic  worms. 

4.  RHIZOPODA.     The  Rhizopods,  or  root-footed  Pro- 
tozoans, (rhiza,  a  root,  and  pous,  foot,)  are  characterized 
by  the   power  of  spontaneously  throwing  out  delicate 
processes  of  their  bioplasm,  called  pseudopodia,  or  false 
feet,  for  prehension  or  locomotion.     They  have  no  cilia. 
Dr.  Carpenter  has  divided  the  class  into  three  orders : 
I.  Reticularia,  whose  bodies  are  indefinite  extensions  oi 
viscid  bioplasm,  freely  branching  and  subdividing  into 
fine  threads,  but  readily  coalescing  when  they  come  into 
contact.     2.  Radiolaria,  whose  bioplasm  has  an  invest- 
ing membrane  of  formed  material  which  prevents  the 
coalescence  of  the  radiating  or   rod-like  extensions  of 
the  pseudopodia.     3.  Lobosa,  whose  bioplasm  has  an  in- 
vesting membrane,  or  ectosarc,  and  whose  false  feet  are 
lobose  extensions  of  the  body  itself. 

In  the  first  order,  that  of  reticularian  rhizopods,  we 


PROTOZOA.  163 

find  many  genera  and  species  which  secrete  a  shell  or 
external  envelope  of  Carbonate  of  Lime,  or  Chalk. 
These  shells  are  often  of  singular  beauty.  They  are 
generally  perforated  by  a  large  number  of  minute  open- 
ings for  the  passage  of  the  pseudopodia,  and  hence  are 
termed  Foraminifera,  {foramen,  an  aperture ;  fero,  I 
carry.)  (Fig.  67.)  Some  of  these  foraminifera  are  sin- 
gle chambers,  often  like  striated  flasks,  (La gen  a  >)  but 


FlG.  67. — Rosalina  ornata,  with  its  pseudopodia  extended. 

others  are  compound,  either  straight,  (Nodosaria,)  spiral, 
(Rotalia,)  or  irregular,  (Globigerina.)  These  shells  are 
generally  microscopic,  although  some,  as  the  Nummu- 
lites,  may  be  an  inch  in  diameter,  and  the  fossil  Eozoon 
Canadense,  which  is  referred  to  this  order,  was  of  indefi- 
nite size.  The  Foraminifera  accumulate  in  the  bed  of 
the  ocean  in  great  numbers,  yet  in  former  ages  they 
were  still  more  prolific,  since  the  Chalk  cliffs  of  England. 


164 


THE  SCIENCE  OF  LIFE. 


the   building-stone   of  Paris,   and   the   limestone  of  the 
Egyptian  pyramids,  are  composed  of  their  remains. 

In  the  Radiola- 
rian  order  is  placed 
the  ActinopJiryssol, 
(Sun-Animalcule,) 
( Fig.  68 ;)  many  spe- 
cies of  Polycystina, 
which  secrete  sili- 
cious  shells,  of  va- 
rious shapes  and  of 
wonderful  beauty, 
(Fig.  69 ;)  and  col- 
onies of  gelatinous 

FIG.  68—  Acrhophrys   sol,  in  different  states.     A.   In      rllizopods,    (TJlCllaS- 
its   ordinary   sunlike  form,  with  a  prominent  contractile 
vesicle,  o.     B.    In  the  act  of  division  or  of  conjugation, 
with  two  contractile  vesicles,  o,  o.  C.  In  the  act  of  feeding.      *  *•»/-«• 
D.  In  the  act  of  discharging  faecal  (?)  matters,   a  and  b.  » 

ule's. 
A 

To  the  order  Lobo- 
sa  belongs  the  Amaba 
princeps,  (Fig.  2,)  to 
which  reference  has 
been  so  often  made, 
since  it  has  occupied 
so  important  a  posi- 
tion in  modern  biolo- 
gy. Chap.  II,  Sees.  2, 

3,5- 

5.  INFUSORIA,  or  An- 
imalcules. The  term 

FIG.  69. — A.  Podocyrtis  Schomburgkii.     B.  Rhopa-  r  .  i  •     j 

locanium  ornatum.  InfuSOHa    IS   applied    tO 


PROTOZOA.  165 

this  class  because  the  species  abound  in  any  infusion 
of  vegetable  or  even  animal  matter  which  is  allowed 
to  putrefy.  The  word  was  formerly  applied  to  a  much 
larger  number  of  species  than  now,  since  many  forms 
once  considered  animal  have  been  placed  in  the  vegeta- 
ble kingdom,  as  the  Desmids,  the  Diatoms,  the  Volvox, 
and  many  other  Protophytes.  The  Rotifers,  or  wheel- 
animalcules,  also,  on  account  of  their  organization,  are 
referred  to  the  articulate  type  of  animal  life.  It  is  pos- 
sible that  some  of  the  Infusoria  may  be  but  larval  forms 
of  higher  animals.  After  all  this  pruning,  however,  the 
class  is  still  a  large  one,  and  full  of  interest.  It  is  divided 
into  three  orders :  Ciliata,  Suctoria^  and  Flagellata. 

Ciliated  Infusoria  (ciliatd)  are  most  numerous,  and  are 
named  from  the  cilia,  or  hair-like  organs,  round  the 
mouth,  or  body,  of  the  animalcule.  Cilia  are  not  con- 
fined to  animalcules.  They  are  found  among  Proto- 
phytes, (Chap.  VI,  Sec.  3.)  They  also  exist  in  many 
organs  of  the  higher  animals,  as  in  the  respiratory  pas- 
sages even  of  man  himself.  They  appear  to  be  tapering 
prolongations  of  bioplasm,  or  of  formed  material  in  con- 
nection with  bioplasm,  and  have  a  sort  of  waving  or 
circular  motion.  In  the  internal  organs  of  man  their 
actions  are  constant,  entirely  without  consciousness,  and 
may  continue  long  after  the  death  of  the  body.  In  the 
animalcules  the  ciliary  action  is  interrupted  and  renewed 
in  such  a  way  as  to  impress  an  observer  with  the  idea  of 
choice  and  direction. 

Vorticella,  or  the  bell-shaped  animalcule,  was  described 
in  Chap.  I,  Sec.  6,  and  the  life-history  there  given  may 
serve  for  a  representation  of  the  entire  order. 


166  THE  SCIENCE  OF  LIFE. 

Epistylis  differs  from  Vorticella  in  having  a  branching 
and  non-contractile  stem. 

Vaginicola  possesses  a  horny,  cuticular  case,  (a  cara- 
pace, or  lorica,}  into  which  the  animal  can  retire. 

Stentor  is  a  fresh-water  infusorian,  shaped  like  a  trum- 
pet. It  may  be  found  either  free  or  attached. 

Paramecium,  (Fig.  70,)  is  a  free,  fresh-water  animal- 


FIG.  70. — Paramecium  Aurelia,  an  Infusorian  animalcule,  magnified  300  times, 

cule,  shaped  like  a  slippe~r,  the  hole  for  the  foot  being 
represented  by  the  mouth. 

Suctorial  Infusoria  (order  Suctoria]  may  be  illustrated 
by  the  parasitic  Acineta,  Chap.  I,  Sec.  6.  They  have 
filaments  ending  in  suctorial  disks,  which  are  capable 
of  protrusion  and  retraction,  and  are  used  for  pre- 
hension. 

The  Flagellate  Infusoria  (order  Flagellata)  perform  lo- 
comotion by  means  of  long  filaments,  or  flagellae,  which 
may  be  single,  double,  or  multiple. 

The  Noctiluca,  (Fig.  71,)  is  the  best-known  member 
of  this  order.  It  is  very  minute,  about  one  eightieth  of 
an  inch  in  diameter,  and  presents  little  more  structure 
under  the  microscope  than  a  simple  sac  of  bioplasm, 
with  vacuoles,  an  oral  aperture,  and  a  tail  of  flagellum, 


PROTOZOA.  167 

but  at  night  these  tiny  beings  light  up  the  ocean  with 
myriads  of  lamps,  whose  phosphorescent  property  is 
yet  a  profound  mystery. 

The  Cercomonady  an  animal- 
cule, with  a  long  flagellum  at 
each  end,  is  noted  for  the  thor- 
ough investigations  made  by 
Messrs.  Dollinger  and  Drysdale. 
These  gentlemen  found  it  would 
increase  for  several  days  by  fis- 

9  FIG.  71. — Noctiluca  miliaris. 

sion.      Then   it  would  lose  the 

flagellae  and  assume  an  amoeboid  form.  Two  of  these 
amoebiform  Cercomonads  would  conjugate  and  become 
encysted,  and  the  rupture  of  the  cyst  gives  exit  to  mi- 
nute germs,  which  grow  into  the  original  parent  form. 
A  temperature  of  150°  F.  sufficed  to  destroy  the  adult 
forms,  but  at  300°  F.  the  germs  still  lived  and  devel- 
oped. This  latter  fact  makes  strongly  against  the  theory 
of  spontaneous  generation. 

6.  SPONGES,  (Spongida.)  What  we  familiarly  call  a 
sponge  is  but  the  skeleton  of  a  colony  of  Protozoa.  In 
this  class  a  number  of  bioplasts,  whose  individuality  is 
still  almost  if  not  complete,  are  united  together,  sup- 
ported on  a  skeleton  of  horny,  silicious,  or  calcareous 
fibers  united  so  as  to  form  a  net-work  of  tubes. 

In  a  living  sponge  currents  of  fluid  set  in  through 
minute  pores  on  the  surface,  and  come  out  in  large 
streams  through  the  larger  apertures,  (oscula^)  These 
currents  are  kept  up  by  the  cilia  connected  with  the  bio- 
plasmic  masses  which  line  the  canals  and  cover  the 
skeleton.  By  means  of  these  currents  particles  of  food 


1 68 


THE  SCIENCE  OF  LIFE. 


are  brought   within  reach  of  the  bioplasts.     (Fig.  72.) 
The  Sponges   are    divided    into   three   orders :    Horny, 


FIG.  72. — Sponge  in  action. 

Silicious,  and  Calcareous  sponges.  In  the  first  order 
(Keratosa)  is  found  the  sponge  of  commerce,  which  owes 
its  value  to  the  fineness  of  its  fibers  and  the  absence  of 
silicious  spicules.  Some  sponges  of  this  order  have 


YIG.  73..  —  a.  Portion  of  Halichondria  (?)  from  Madagascar,  with  spicules  projecting 
from  the  fibrous  network,    b.  Silicious  Spicules  of  Pachymatisma. 

•flinty  spiculse  of  various  shapes,  as  pins,  clubs,  crosses, 
hooks,   and  anchors.     (Fig.  73.)     The  silicious  sponges 


PROTOZOA.  169 

(Silicea)  sometimes  have  their  spicules  woven  or  fused 
together,  as  in  the  beautiful  Euplectella,  or  Venus's 
Flower-basket.  In  Hyalonema,  the  glass-rope,  the  long 
spicules,  are  twisted  together. 

In  the  order  Calcarea  the  skeleton  is  composed  of  Car- 
bonate of  lime.  Except  a  few  fresh-water  species,  as 
Spongilla,  sponges  are  marine.  The  best  sponges  of 
commerce  are  from  the  Mediterranean. 

7.  The  colonies  of  bioplasts  in  Thalassicollida  and  in 
Sponges  are  analogous  to  the  higher  types  of  animal  life, 
yet  the  individual  cells  are  so  loosely  bound  together, 
and  so  capable  of  living  and  performing  all  their  func- 
tions apart,  that  they  are  ranked  as  Protozoa,  as  the  col- 
onies of  Volvocineae,  Nostochaceae,  and  Confervaceae,  are 
placed  among  the  Protophytes. 

8.  The  essential  difference  in  the  vital  powers  of  dif- 
ferent classes  of  living  things,  and  of  the  individuals  of 
each  class,  is  well  exhibited  in  the  following  passage  from 
Johnston's  "  British  Sponges  :"  4<  For  example,  it  is  very 
common  to  find  growing  on  the  same  rock,  or  sea-weed, 
a  silicious,  a  calcareous,  and  a  horny  sponge  ;  they  have 
all  the  same  exposure,  and  are  all  recipients  of  the  same 
nutriment,  yet  does  each  act  upon  this  differently.     One 
extracts  from  the  fluid  silica,  which  it  causes  to  assume 
a  solid  crystalline  form  ;   another   selects   in   the  same 
manner  the  calcareous  particles,  which,  obedient  to  the 
laws  of  life,  assume  figures  novel  to  them  in  their  min- 
eral state  ;  and  again,  another  rejects  both  the  lime  and 

the  flint  as  injurious  to  its  constitution." 
15 


170  THE  SCIENCE  OF  LIFE. 


CHAPTER  XII. 

RADIATA. 

If  we  are  astonished  that  so  great  deeds  should  proceed  from  the  little 
and  low,  it  is  because  we  fail  to  appreciate  that  little  things,  even  the  least 
of  living  or  physical  existences  in  nature,  are,  under  God,  expressions 
throughout  of  comprehensive  laws,  laws  that  govern  alike  the  small  and 
the  great. — DANA,  Corals  and  Coral  Makers. 

1.  IN  the  simple  Protophytes  and  Protozoa  we  find  the 
essential  structure  to  be  a  single  cell,  or  mass,  of  bio- 
plasm, having  in  one  vegetable  and  in  the  other  animal 
characteristics.     In  some  instances  there  is  a  colony,  or 
association,  of  bioplasts,  with  certain  mutual  relations ; 
but  as  each  bioplast  is  but  loosely  connected  with  the 
others,  and  is  capable  of  living  and  performing  all  its 
functions  while  in  a  state  of  independence,  these  colo- 
nies are  conveniently  considered  among  primordial  types. 
In  the  higher  forms  of  life,  either  animal  or  vegetable, 
each  individual  is  composed  of  many  bioplasts,  derived 
by  subdivision  of  the  primitive  mass.     With  the  division 
of  the  structure  there  is  also  a  differentiation  of  function, 
so  that   no  bioplasts  of  the  structure,  save  those  which 
are  appropriated  to  reproduction,  can  normally  pursue 
an  independent  existence. 

2.  The  Radiate  type  of  animal  life  is  characterized  by 
the  idea  expressed  in  the  word  radiation.     "  In  Radiates 
we  have  no  prominent  bilateral  symmetry,  such  as  ex- 
ists in  all  other  animals,  but  an  all-sided  symmetry,  in 


RADIATA.  171 

which  there  is  no  right  and  left,  no  anterior  and  poste- 
rior extremity,  no  above  and  below.  It  is  true  that  in 
some  of  them  there  are  indications  of  that  bilateral  sym- 
metry which  becomes  a  law  in  the  higher  animals  ;  but 
whenever  such  a  tendency  is  perceptible  in  the  Radiates 
it  is  subordinate  to  the  typical  plan  on  which  the  whole 
group  is  founded."  * 

3.  Radiate   animals   are   subdivided    into  I.  CcELEN- 
TERATA,  or  Ccelenterates,  (koilos,  hollow  ;  enteron,  intes- 
tine,) or  animals  with  an  alimentary  canal  communicating 
with  the  general  cavity  of  the  body ;  and,  II.  ECHINO- 
DERMATA,    (echinos,   a    spine ;    derma,  skin,)    or   spiny- 
skinned  animals.     Other  characteristics,  however,  besides 
those  signified  in  the  names  of  these  sub-types  are  nec- 
essary to.  be  considered. 

4.  The  CCELENTERATA  are  radiate  animals  with  a  dis- 
tinct body-cavity,  whose  walls  consist  of  two  layers  of 
cellular  tissue,  an  outer  (ectoderm)  and  inner,  (endodenn,) 
and  contain  nettling  thread-cells,  or  small  sacs  full  of 
fluid  connected  with  barbed  filaments,  capable  of  being 
projected  for  stinging  purposes.     Most  of  these  animals 
have  hollow  tentacles  round  the  mouth.     There  are  two 
large  classes  of  Ccelenterates :  I.  The  HYDROZOA,  which 
have  no  digestive  cavity  separate  from  the  rest  of  the 
mass  which  forms  the  body,  and  whose  reproductive  or- 
gans are  external ;  and,  II.   ACTINOZOA,  which  have  a 
digestive  canal  distinct  from  the  rest  of  the  body,  sus- 
pended by  radiating  partitions,  called  mesenteries ;  and 
whose  organs  of  reproduction  are  internal,  placed  on  the 
mesenteries.     The  first  of  these  classes   may  be  repre- 

*  Agassiz. 


1/2 


THE  SCIENCE  OF  LIFE. 


sented  by  the  Hydra,  and  the  latter  by  the  Sea-anem- 
one, or  Actinia. 

The  Hydra  is  named  after  a  fabled  monster  that  re- 
produced its  heads  as  fast  as  they  were  cut  off.     The 

genus  comprises  two  species, 
the  green  and  the  brown 
Hydra,  (H.  viridis  and  H. 
fusca.)  (Fig.  74.)  They  are 
minute  creatures,  about  a 
quarter  of  an  inch  long,  gen- 
erally found  on  the  under 
surface  of  aquatic  plants,  at- 
tached by  a  disk,  while  their 
long  tentacles  float  down- 
ward in  search  of  prey.  The 
body  is  a  simple  tube,  or 
cavity,  and  the  tentacles 
are  supplied  with  "  lasso- 
threads,"  or  nettling  thread- 
cells.  In  the  early  summer 
small  buds  grow  from  the 
base  of  the  body,  which  grow 
into  the  likeness  of  the  par- 
FIG.  74.-Hydra  fusca,  with  a  young  bud  ent,  and  then  are  detached. 

at  b.  and  a  more  advanced  bud  at  c.  o  .  ,  /» 

Sometimes  a  second  crop  01 

buds  arise  from  the  first  before  it  is  separated.  Later  in 
the  season  eggs  form  from  modified  cells  of  the  inner 
layer,  which  burst  through  the  outer  layer,  become  free, 
and  develop  into  new  Hydrae. 

These  animals  are  nearly  allied  to  the  Protozoa,  since 
the  differentiation  of  function  in  the  bioplasts  is  incom- 


RADIATA.  173 

plete.  Hence  the  wonderful  powers  of  propagation  in 
these  creatures,  which  have  astonished  naturalists  ever 
since  Trembley  first  discovered  them,  in  1744.  He  says  : 
"  I  have  opened  a  polyp  on  my  hand,  extended  it,  and 
cut  the  simple  skin  of  which  it  is  formed  in  every  direc- 
tion ;  I  have  reduced  it  to  little  pieces,  and,  in  a  man- 
ner, minced  it.  These  little  pieces  of  skin,  both  those 
which  did  and  those  which  did  not  possess  arms,  became 
perfect  polyps."  Many  curious  multiple  forms  have 
been '  produced  by  experiments  on  these  animals.  By 
slitting  the  body  into  two  branches,  and  these  branches 
again  into  others,  a  tree-like  form  may  be  produced,  each 
branch  giving  rise  to  a  distinct  head  and  tentacles.  Or 
one  may  be  turned  inside  out  like  a  glove,  so  that  the 
outer  skin  becomes  the  lining  of  the  stomach-cavity,  with 
a  transposition  of  the  functions  of  each. 

Order  I.  Hydroida.  This  order  is  composed  of  ani- 
mals built  on  the  pattern  of  the  Hydra,  just  described. 
They  are  either  single,  as  the  Hydra,  or  compound.  The 
latter  are  subdivided  into  the  three  families  of  Campanu- 
larians,  Sertularians,  and  Tubularians.  They  are  grouped 
in  clusters  or  colonies  on  a  common  axis  or  stalk,  (cceno- 
sarc^)  Each  hydra-like  organism  is  called  a  polypite. 
New  polypites  arise  as  outgrowths  from  the  common 
stem  of  the  colony,  so  that  the  stomach  of  each  is  con- 
tinuous with  the  tubular  center  of  the  stalk,  producing  a 
community  of  nutrition  in  the  colony.  In  Chap.  III., 
Sec.  14,  reference  was  made  to  the  alternation  of  genera- 
tions which  this  order  of  animals  so  strikingly  illustrates. 
This  process  in  the  life-history  of  the  Hydroids  is  briefly 

as  follows :    The   Polyp,   a   fixed   animal,   increases  for 
15* 


THE  SCIENCE  OF  LIFE. 

awhile  by  budding,  but  at  a  certain  period  gives  birth 
by  subdivision,  to  free  swimming  Medusae,  or  Jelly-fish 
Each  of  these,  after  pursuing  for  a  time  its  own  course 
of  life  and  development,  produces  eggs  which  change 
into  ciliated  bodies  (Planuld)  similar  to  some  of  the  In- 
fusoria. After  a  while  each  of  these  becomes  stationary, 
fixes  itself  to  some  weed  or  rock,  and  becomes  a  polyp, 
or  Hydroid. 

Those  Medusae  which  swim  by  the  contraction  of  their 
umbrella-like  disk  were  formerly  called  Pulmogrades ; 
those  which  swim  by  vibratile  cilia  attached  to  arms, 
Ciliogrades ;  those  which  float  by  an  expansive  bladder, 
Physogrades ;  and  those  furnished  with  arms,  or  cirri, 
Cirrigrades.  Another  classification  divided  them  into 
"  naked-eyed "  and  "  hidden-eyed  "  Medusae.  Since 
more  thorough  research  has  shown  their  relation  to  the 
Hydroids,  the  Medusae  have  been  considered  in  reference 
to  the  families  of  Hydroids  from  which  they  springe 

The  Tubularian  family  (tubulus,  a  little  tube)  consist 
of  Hydroids,  sometimes  simple,  but  generally  compound, 
united  by  a  common  trunk  or  coenosarc,  which  has  an 
external  horny  coat,  or  polypary.  Sometimes  the  tube 
is  jointed  with  the  tentacles  placed  in  a  whorl  round  each 
joint,  (Tubularida  divisa^}  sometimes  it  is  undivided, 
(71  indivisa^}  Sometimes  the  polypary  is  much  branched, 
(as  in  Eudendrium?)  but  in  the  majority  it  is  not  branched. 
A  few  species  have  no  hard  polypary,  (as  Corymorpha 
nutans^)  but  simply  a  white  fleshy  stem.  The  polyps  of 
this  family  have  no  protecting  cups.  The  Medusae  bud 
from  the  stem. 

The  Sertularian  family  (Sertula,  a  little  wreath)  is  gen- 


RADIATA. 


175 


erally  regarded  as  a  sea-weed  by  sea-side  visitors,  but  a 

very  cursory  examination  with  a  pocket  lens  will  suffice 

to  show  the  horny  and  branched  polypary,  with  its  little 

cups,  (Itydrothecce?) 

which  contain  and 

protect  the    poly- 

pites.     In  some  of 

the       Sertularians 

the  Medusae  wither 

on  the  stock,  never 

becoming  free. 

The  Campanula- 
rian  family  (Cam- 
panula, a  little  bell) 
resemble  Sertula- 
rians, except  that 
the  cups  (Jtydro- 
thecce)  are  stalked 
and  terminal  in- 
stead of  being  lat- 
eral and  sessile,  as 
in  the  latter.  The 
reproductive  caly- 
ces, or  ovarian  cap- 
sules, may  contain 

many       Medusae         FIG.  75.-Campanularia  gelatinosa  :— A.  Upper  part  of 
L       j          i  i  ,      the  stem  and  branches,  of  the  natural   size.     B.  A  small 

evelOped      portion   enlarged,  showing  the  structure  of  the  animal. 
One  below  the  Oth-      a'  Terminal  branch  bearing  polyps,      b.  Polyp  bud  par- 
tially developed,     c.  Horny  cell,  containing  the  expanded 

er,  which    are   Set      P°lyPi  ^.       e-  Ovarian  capsule,    containing   medusiform 
gemmae  in  various  stages  of  development,    f.  Fleshy  sub- 
free  by  the  bursting      stance  extending  through  the  stem  and  branches,  and  con- 
11     /•  necting    the    different  polyp-cells  and  ovarian  capsules. 

O*  the  Cell.  (P  Ig.  75  •)     £•  Annular  constrictions  at  the  base  of  the  branches. 


176  THE  SCIENCE  OF  LIFE. 

The  ordinary  Jelly-fish  (Medusa,  or  Acalepli]  is  soft, 
gelatinous,  and  bell-shaped,  with  tubes  radiating  from 

center  to  circumfer- 
ence, where  they  con- 
nect with  a  circular 
canal.  The  margin  is 
fringed  with  stinging 
tentacles.  The  radi- 
ating parts  are  in  mul- 
tiples of  four.  These 
gelatinous  bells,  vary- 
ing from  the  size  of  a 
pea  to  a  foot  or  more 
in  diameter,  float, 

FIG.  76.  —  Development  of  Snrsia.     i.  Polyps  de- 
scribed  as   Syncoryne,    natural    size.      2.    A   polyp,  mOUth    downward,    ill 
magniried.      a.   Polyp  stem.      b.  c.  d.  e.    Medusoid  n                                   . 
buds,  in  various  stages.    /.  Tentacles  of  the  polyp,  the     SCa,     and     propel 

themselves  by  flap- 
ping their  sides.  (Fig.  76.)  There  are  two  representa- 
tive forms  of  Medusae,  the  Lucernaria,  or  Umbrella-aca- 
leph,  attached  by  a  short  pedicle,  and  having  tentacles 
disposed  in  eight  groups  around  the  margin,  and  not  less 
than  eight  radiating  canals ;  and  Discophora,  the  ordi- 
nary Jelly-fish,  free  and  oceanic,  with  four  radiating 
canals  in  the  disk,  which  ramify  and  open  into  a  circular 
canal  around  the  mouth  of  the  disk. 

Order  2.  Siphonophora,  or  floating  Hydroids,  (siphon, 
a  curved  tube,  and  phero,  to  bear,)  are  free  swimming  or 
compound  floating  Hydroids,  with  an  unbranched,  or 
slightly  branched,  but  muscular  ccenosarc.  The  com- 
mon stem  of  these  colonies  swims  by  means  of  enlarged 
and  altered  polyphites,  whose  stomachs  are  undeveloped 


RADIATA. 


177 


and  whose  bodies  are  dilated.  Some  possess,  also,  a  sac 
filled  with  air,  which  acts  as  a  float,  as  the  Physalia, 
(physa,  a  bubble,)  or  Portuguese 
Man-of-war,  whose  purple-crest- 
ed air-sac  and  long  tentacles  at- 
tract such  attention  in  tropical 
seas,  and  whose  thread-cells  in- 
flict such  painful  stings  when 
grasped  by  an  incautious  hand. 
(Fig.  77.)  The  Porpita  {porpc, 
the  ring  of  a  shield)  possesses 
an  internal  skeleton,  or  flat 
plate,  of  cartilaginous  texture, 
which  is  cellular  and  lighter  than 
water.  Its  lower  surface  con- 
tains a  beautiful  fringe  of  blue 
tentacles,  or  cirri.  In  the  Vel- 
ella  (velella,  a  little  sail)  a  second  FlG>  77'-physalia' 

cartilaginous  plate  rises  nearly  at  right  angles  from  the 
upper  surface  of  the  horizontal  one,  serving  as  a  sail  to 
waft  the  little  mariner  from  place  to  place. 

CLASS  II.  AcTINOZOA,  (actin,  a  ray;  zoon,  an  animal.) 
This  class  embraces  the  Sea-anemones,  the  Corals,  and 
the  Ctenophora,  (kteis,  a  comb ;  phero,  I  bear,)  or  comb- 
bearing  Medusae.  The  digestive  cavity  is  suspended  in 
the  body  cavity,  like  a  small  bag  within  a  larger  one,  by 
vertical  partitions,  some  of  which  extend  from  the  body- 
wall  to  the  digestive  sac,  but  others  fall  short  of  it. 
Upon  these  septa,  or  mesenteries,  are  the  organs  of  re- 
production. The  ectoderm  is  more  highly  developed 
.than  in  Hydrozoa,  and  both  mesenteries  and  body-walls 


i;8  THE  SCIENCE  OF  LIFE. 

are  supplied  with  distinct  sets  of  muscles.  Cilia  are 
present  on  the  digestive  tube,  producing  a  current  both 
respiratory  and  circulatory. 

The  Actinia,  or  Sea-anemones,  are  the  much-admired 
forms  so  often  seen  in  the  rock-pools  around  our  shores, 
sometimes  called  animal  flowers,  attached  to  the  rocks 
by  a  flat  disk,  expanding  their  petal-like  tentacles  in 
search  of  prey,  and,  when  uncovered  by  the  retreating 
tide,  contracting  into  small  round  gelatinous  masses. 


A  B 

FIG.  78. — A.  Sea-anemone,  seen  from  above.     B.  Section  of  Sea-anemone,    a.  Cavity 
of  stomach,    b.  Surrounding  chambers. 

The  tentacles  and  partitions  of  the  body  are  in  multi- 
ples of  six.  Fig.  78  represents  the  internal  form  of 
Actinia. 

The  Coral  polyps  are  Actinozoa,  which  secrete  coral, 
generally  composed  of  carbonate  of  lime,  but  it  is  occa- 
sionally horny,  or  a  mixture  of  horny  and  calcareous 
matter.  These  polyps  are  usually  found  in  colonies 
formed  by  a  continuous  process  of  budding.  The  com- 
pound mass  is  like  a  sheet  of  animal  matter,  fed  and 
nourished  by  numerous  mouths  and  many  stomachs. 
Corals  are  of  two  kinds,  the  sclerobasic  and  sclerodermic 
corals.  The  polyps  of  the  latter  resemble  Actiniae  in 
structure.  The  earthy  matter  is  secreted  between  each 


RADIATA. 


179 


pair    of   partitions,    so    that    the    skeleton    ot    a   single 
polyp   (or   corallite)  is  a  short   tube  with  vertical  septa 


FIG.  79. — Corals. 

radiating  toward  the  center.  The  Fungia,  or  Mush- 
room coral,  is  disk- 
shaped,  and  differs 
from  others  in  not 
being  either  fixed  or 
compound.  It  is  sim- 
ply the  skeleton  of  a 
single  polyp,  showing 
a  radiating  secretion 
of  calcareous  septa. 
The  various  kinds  of 
budding  in  compound 
coral-polyps  give  ris- 
to  a  variety  of  shapes, 
either  dome -like  or  FIG.  8o,-Madrepore. 


i8o  THE  SCIENCE  OF  LIFE. 

branching.  Astrcea  is  a  hemispherical  mass  covered  with 
large  cells.  Meandrina,  or  "  Brain-coral,"  has  the  mouths 
of  the  polyps  opening  into  each  other,  forming  furrows. 
(Fig.  79.)  Madrepore  branches,  like  a  tree,  with  pointed 
extremities.  (Fig.  80.) 

Sclerobasic  corals  are  those  which  secrete  coral  by  the 
outer  layer  of  the  inverted  ectoderm.  Most  of  these 
are  of  the  order  Alcyonaria,  whose  polyps  are  character- 
ized by  primate  or  fringed  tentacles  in  multiples  of  four, 
while  the  sclerodermic  corals  generally  belong  to  the 
order  Zoantharia,  with  polyps  having  simple  tentacles  in 
multiples  of  five  or  six.  The  characters  of  Alcyonarian 
polyps  may  be  seen  by  placing  in  sea-water  some  of 
those  large  yellowish,  gristly  masses,  sometimes  cast  up 
by  the  sea,  known  as  "  dead  men's  fingers."  From  the 


FIG.  81.— i.  Sea-fan.     2.  Sea-pen. 


surface  of  each  pore  the  tentacles  round  the  mouth  of 
the  polyps  will  protrude,  showing  their  general   resem- 


RADIATA.  181 

blance  to  Actinia.  Minute  spicules  of  calcareous  matter 
are  scattered  throughout  the  mass.  In  Gorgonia  such 
spicules,  with  horny  matter,  make  up  a  continuous 
branching  coral  in  the  same  plane,  whose  ramifications 
unite  in  a  beautiful  net-  work.  (Fig.  81.)  In  Corallium 
rubrum,  the  precious  coral  of  commerce,  the  axis  is  of 
stony  hardness,  and  branching  like  a  shrub.  In  the 


FIG.  82.— Red  Coral. 


FIG.  83.—  Tubicora  Musica.—  Organ-pipe  Coral. 


living  state  the  branches  are  covered  with  a  red  cceno- 
sarc,  (common  flesh,)  studded  with  polyps.  (Fig.  82.) 
The  feather-shaped  sea-pens  (Pennatula]  have  the  ex- 
tremities of  their  stems  buried  in  sand.  In  some  genera, 
as,  Virgularia,  the  stem  is  prolonged  to  between  three 
and  four  feet  in  length,  while  the  polypiferous  lobes  are 
comparatively  short.  The  red  organ-pipe  coral  of  the 
Indian  Ocean,  (Fig.  83,)  with  its  table-like  partitions  and 

green  polyps,  belong  also  to  this  group. 
16 


182 


THE  SCIENCE  OF  LIFE. 


The  work  of  the  reef-building  polyps  is  extremely 
interesting.  They  will  not  live  in  water  whose  mean 
temperature  is  below  68°  F.,  nor  at  a  greater  depth  than 
twenty  fathoms,  yet  coral  reefs  are  constantly  found 
which  are  several  hundred  fathoms  thick.  This  appar- 
ent paradox  is  due  to  the  fact  that  the  land  where  coral 
reefs  are  forming  is  constantly  subsiding,  and  fresh  living 
corals  are  taking  the  place  of  the  dead  ones.  If  the 
center  of  a  reef  sinks  more  quickly  than  the  sides  a 
lagoon  is  left,  surrounded  by  a  circular  reef  of  coral, 
called  an  atoll ;  if  an  island  rises  in  the  middle  of  this 
lagoon  a  barrier  reef  is  said  to  be  formed,  (Fig.  84;) 
while  if  the  sea  clearly  intervenes  between  the  reef  and 


FIG.  84.— A  Coral  Island. 


the  mainland,  we  have  what  is  termed  a  "  fringing  ree*"." 
Different  species  of  polyps  build  these   reefs.      Madre- 


RADIATA. 


•83 


pores,  Millepores,  and  Gorgonidae  work  chiefly  at  the 
top,  next  below  we  meet  with  Meandrinas,  and  lowest 
of  all,  with  Astraeans. 

The  Ctenophorce,  or  comb-bearing  Medusae,  exhibit 
traces  of  a  nervous  system  in  a  ganglionic  mass  at  the 
upper  end,  or  pole,  of  the  animal,  with  nervous  filaments 
radiating  to  every  part  of  the  body.  They  are  trans- 
parent gelatinous  animals,  which  swim  freely  by  means 
of  bands  of  comb-like  fringes  or  paddles.  Their  internal 
structure  is  quite  complex,  having  a  distinct  alimentary 
canal,  and  ducts  for  the  circulation  of  fluid.  They  are 
retained  in  the  Radiate  type,  on  account  of  the  radiate 
arrangement  of  the  bands  of  cilia  and  the  presence  of 
urticating  organs  on  the  tentacles,  although  their  affini- 
ties would  seem  to  place  them  elsewhere. 

The  Beroe  and  Cydippe  (Fig.  85)  and  Cestum  Veneris, 


FIG.  85. — A.  Cydippe  pileus,  with  its  tentacles  extended.     B.  Beroe  Forskalii,  showing 
the  tubular  prolongations  of  the  stomach. 

or  Girdle  of  Venus,  belong  to  this  order.  In  the  latter, 
the  sides  are  prolonged  into  a  ribbon,  although  the 
mouth  and  digestive  organs  are  confined  to  the  middle 


1 84  THE  SCIENCE  OF  LIFE. 

of  the  body.  In  the  day-time  its  waving  cilia  along  the 
margins  of  the  body  glitter  with  the  tints  of  the  rainbow, 
and  at  night  it  appears  like  a  long  waving  flame  in  the 
water. 

5.  The  subtype  of  Radiate  animals,  called  ECHINO- 
DERMATA,  is  distinguished  by  the  possession  of  a  nervous 
system,  in  the  form  of  a  pentagonal  ring  round  the 
mouth ;  an  alimentary  canal,  with  oral  and  anal  aper- 
tures ;  a  peculiar  system  of  circular  and  radiating  canals ; 
and  a  symmetrical  arrangement  of  all  the  parts  of  the 
body  around  a  central  axis,  in  multiples  of  five.  Some 
star-fishes  (Solaster)  have  twelve  rays.  In  all  Echino- 
derms,  probably,  sea-water  is  freely  admitted  into  the 
body-cavity  around  the  viscera.  The  canals  likewise 
contain  water,  which  enters  through  a  porous  tubercle, 
the  madreporic  plate,  or  dorsal  wart,  best  seen  on  the 
back  of  the  star-fish  and  the  sea-urchin.  Some  natural- 
ists rank  Echinoderms  as  Worms. 

The  Crinoidea,  or  Sea-lilies,  so  called  from  their  re- 
semblance to  flowers,  are  fixed  to  the  sea-bottom  by  a 
hollow,  jointed,  flexible  stem,  which  carries  the  body, 
which  is  cup-shaped,  with  radiating  arms,  or  tentacles. 
This  order  includes  an  immense  number  of  fossil  forms, 
but  deep-sea  dredging  has  brought  up  many  living 
species,  formerly  thought  to  belong  exclusively  to  the 
Mesozoic  period.  They  all  possess  an  internal  skeleton 
of  infiltrated  calcareous  matter,  so  that  the  entire  animal 
consisted  of  thousands  of  stellate  pieces,  or  joints,  con- 
nected by  animal  matter.  As  each  joint  is  furnished 
with  at  least  two  bundles  of  muscular  fiber,  one  for  ex- 
tension and  one  for  contraction,  Dr.  Carpenter  esti- 


R  ADI  ATA.  185 

mates  three  hundred  thousand  such  muscles  in  a  single 
Pentacrinus — an  amount  of  muscular  apparatus  far  ex- 
ceeding any  that  has  been  elsewhere  observed  in  the 
animal  creation.  The  family,  COMATULlDyE,  or  Hair- 
stars — sometimes  termed  Feather-stars — in  their  young 
condition,  resemble  the  Encrinites,  or  Sea- lilies,  being 
supported  on  a  long  flexible  stalk,  composed  of  calcare- 
ous cylinders.  At  maturity  they  quit  their  attachment, 
and  crawl  about  like  other  Star-fishes. 

The  order  ASTEROIDEA,  or  Star-fishes,  consists  of  ani- 
mals with  a  flat  central  disk,  having  five  or  more  arms, 
or  lobes,  radiating  from  it,  and  containing  branches  of 
the  viscera.  The  skin  is  leathery,  hardened  by  small 
calcareous  plates,  (eleven  thousand  or  more,)  but  some- 
what flexible.  The  mouth  is  below,  and  the  rays  are 
furrowed  underneath  and  pierced  with  numerous  holes 
through  which  pass  sucker-like  tentacles  for  locomotion 
and  prehension.  These  furrows  are  named  ambulacra, 
or  avenues,  from  a  fancied  resemblance  to  a  walk,  or 
alley,  in  a  garden.  As  the  tentacles,  or  suckers,  are  only 
protruded  from  these  spaces,  they  also  have  been  called 
ambulacra.  The  arrangement  for  their  protrusion  will 
be  described  in  connection  with  the  Sea-urchins,  as  well 
as  the  Pedicellaria  (formerly  believed  to  be  parasitic  or- 
ganisms) found  near  the  mouth. 

About  one  hundred  and  fifty  species  of  Star-fishes  are 
known,  divided  into  three  groups:  (i.)  those  having  four 
rows  of  feet,  as  the  common  five-fingered  Star-fish,  or 
Asterias ;  (2.)  those  with  two  rows,  as  the  many-rayed 
Solaster,  or  Sun-fish,  and  the  pentagonal  Goniaster  ; 

(3.)  those  with  long  slender  arms,  which  are  not  prolon- 
16* 


1 86  THE  SCIENCE  OF  LIFE. 

gations  of  the  body,  and  are  not  provided  with  suckers, 
as  the  Ophiura,  or  Brittle-star,  (Fig.  86,)  and  Asterophy- 

ton,  or  Basket-fish.  The  last 
group  are  inferior  in  struct- 
ure, and  resemble  inverted 
stemless  Crinoids.  The  di- 
gestive sac  is  confined  to  the 
disk,  and  the  madreporic 
plate  is  underneath. 

The    order    ECHINOIDEA, 
FIG.  se.-Ophiura.  Or  Sea-urchins,  contains  those 

Echinoderms  whose  skin  secretes  calcareous  plates,  form- 
ing a  hollow  shell,  covered  with  spines,  and  varying  in 
shape  from  a  sphere  to  a  disk.  The  shell  of  an  Echinus 
is  made  up  of  twenty  rows,  or  zones,  of  plates,  of  which 
five  pairs  are  ambulacral,  pierced  with  minute  pores  for 
the  protrusion  of  ambulacra,  or  sucker-feet,  and  five  pairs 
alternating  with  the  former  are  inter-ambulacral.  The 
shell  is  developed  from  a  membrane  which  lines  the  in- 
terior of  the  plates,  and  passes  between  the  joints,  so 
that  additions  can  be  made  to  their  edges,  by  which 
means  the  shell  grows  and  preserves  the  same  relative 
proportions.  The  upper  end  of  the  shell,  in  addition  to 
five  small  circularly  disposed  plates,  carries  five  large 
genital  plates.  Each  of  these  has  a  duct  for  the  passage 
of  ova  or  spermatazoa,  and  an  ocellus,  or  eye-spot.  One 
of  these  plates  is  the  madreporic  tubercle,  with  minute 
apertures  communicating  with  the  madreporic  canal. 
Locomotion  is  effected  by  the  hollow  muscular  feet, 
each  of  which  communicates  with  a  water  sac ;  they 
also  communicate  with  each  other,  so  that  as  each 


RADIATA. 


sac  contracts,  water  is  forced  into  the  corresponding  tube, 
which  is  thereby  elongated  and  protruded.   (Fig.  87.) 


1 


FIG.  87. — Morphology  of  Echinoidea.  i.  Echmid  larva,  a.  Mouth,  b.  Stomach,  c.  In- 
testine, s.  Skeleton.  2.  Diagram  of  Echinus.  The  spines  and  the  ambulacra  are  repre- 
sented over  a  small  portion  of  the  test ;  the  vascular  system  is  cross-shaded  ;  the  nervous 
system  is  represented  by  the  black  line.  a.  Anus.  b.  Stomach,  c.  Mouth.  da.nAf.  Vas- 
cular rings  round  the  alimentary  canal,  e.  Heart,  g.  Test.  k.  Nervous  ring  round  the 
gullet,  i.  Ambulacral  ring,  or  circular  canal  round  the  gullet,  k  k.  Polian  vesicles.  /.  Sand 
canal,  m  m.  Radiating  ambulacral  canal.  ».  Secondary  ambulacral  vesicles,  o.  Ambu- 
lacra, or  "  tube-feet."  p.  Spines,  r.  Madreporiform  tubercle. 

The  shell  of  the 
Echinus  is  cov- 
ered with  semi- 
globular  warts, 
or  beads,  each 
of  which  during 
life  supports  a 
sculptured  spine 
with  a  hollow  at 
its  base,  forming 

FIG.  88. — Shell  of  Echinus,  or  Sea-urchin  ;  on  the  right  side, 
and    ligaments    a  covered  with  spines  ;  on  the  left,  the  spines  removed. 

ball  and   socket  joint,  subsidiary  to  locomotion.    (Figs. 
88  and  89.)      Pedicellarice  are  minute,  almost  microscopic, 


88 


THE  SCIENCE  OF  LIFE. 


jointed  spines,  scattered  all  over  the  shell  of  the  Echinus, 
and  terminated  by  a  three-  fold  claw,  capable  of  being 


FIG.  89. — Morphology  of  Echinoidea.  i.  Portion  of  the  test  of  Galerites  hemisphericus 
enlarged,  showing  the  inter-ambulacral  area  (a)  and  the  ambulacral  areas,  (£.)  2.  Galer- 
ites hemisphericus  viewed  from  above,  a.  Inter-ambulacra,  b.  Ambulacra.  3.  Genital 
and  ocular  disk  of  Hemicidaris  intermedia,  enlarged,  c.  Ocular  plate,  d.  Genital  plate. 
e.  Anal  aperture,  f.  Madreporiform  tubercle.  4.  Spine  of  the  same.  (After  Forbes.) 
The  tubercles  are  mostly  omitted  on  figs.  2  and  3  for  the  sake  of  clearness. 

closed  like  a  pair  of  forceps  upon  animalculae  or  other 
offensive  matter  that  may  tend  to  obstruct  its  shell.  One 
carries  the  rejected  matter  to  another  till  the  surface  is 
completely  free. 

The  mouth  of  an  Echinus  contains  the  most  complex 
and  perfect  dental  apparatus  in  all  the  Animal  Kingdom, 
although  occurring  in  a  type  generally  considered  of  a 
low  grade  of  structure.  It  sets  at  naught  all  theories  of 
Evolution,  since  in  our  progress  from  the  simplest  forms 
of  life  it  is  the  first  instance  of  a  dental  apparatus,  and 
the  most  perfect  of  all.  It  is  composed  of  five  accurately- 
htting  vertical  pyramids,  each  provided  with  a  rod-like 
tooth,  worked  by  a  couple  of  beautifully  arranged  mus- 
cles. (Fig.  90.)  The  intestine  is  tortuous  and  connected 


KADIATA. 


189 


a 


a 


by  delicate  mesenteries  to  the  shell.  These  animals  pos- 
sess a  heart  with  an  aorta  surrounding  the  gullet  and  in- 
testine. The  blood 

is   aerated   by  ex-  o 

posure  to  the  ox- 
ygen mixed  with 
the  water  which  is 
constantly  circula- 
ting over  the  vas- 
cular mesenteries. 

The  metamor- 
phosis of  Echinus  is 
very  curious.  The 
embryo  is  a  free 
swimming  minute 
ciliated  creature, 
strangely  like  a 
painter's  easel,  and 
hence  called  a  Pluteus.  \_Pluteus,  a  penthouse.]  This 
passes  through  a  strange  cycle  of  changes.  The  diges- 
tive canal  appears  in  the  middle  of  the  frame,  which 
gradually  disappears,  the  future  Echinus  is  sketched  in, 
and  a  radially  symmetric  animal  results,  totally  unlike  its 
predecessor.  (Fig.  91.) 

Regular  Echini,  as  the  common  Cidaris,  are  nearly 
globular,  and  the  oral  and  anal  openings  are  opposite. 
Irregular  Echini,  as  the  Clypeaster  and  Spatangus,  are 
flat,  or  discoid,  with  hair-like  spines,  and  the  rows  of  am- 
bulacra form  a  five-rayed  star  on  the  back  of  the  shell. 
Spatangus  has  no  dental  apparatus. 

The  order  HOLOTHUROIDEA,  embraces  what  are  com- 


FIG.  90. — Dentary  Apparatus  of  Echinus,  or  Aristotle's 
Lantern.  The  right-hand  diagram  shows  three  of  the  teeth 
in  position,  a  a.  Cutting  edges  of  the  teeth,  which  are  ex- 
tremelyhard.  b.  Fibrous  roots  of  the  teeth,  cc.  Opposed 
bony  surfaces  of  the  jaws,  d  d.  Arched  processes.  The 
left-hand  diagram  shows  an  isolated  pyramid,  e.  Exter- 
nal surface.  Other  letters  as  before. 


190 


THE  SCIENCE  OF  LIFE. 


monly  known  as  Sea-slugs,  Sea-cucumbers,  or  Trepangs. 

The  body  is  elongated  and  soft,  with  a  tough  contractile 

skin  containing  calca- 
reous spicules.  One 
end,  the  head,  has  a 
simple  aperture  for 
a  mouth,  encircled 
with  feathery  tenta 
cles.  In  the  Holo- 
thurice  proper,  loco- 
motion is  effected  by 
rows  of  ambulacral 
tube-feet,  but  in  the 
Synaptidce  there  are 
no  ambulacra,  and 
the  animal  moves 
9  by  means  of  anchor- 
shaped  spicuta  which 
are  scattered  in  the 
integument.  Animals 
of  this  order  have 

FIG.  91. — Embryonic   development   of  Echinus: —  the  singular  DOWCr  of 
A.  Pluteus  larva  at  the  time  of  the  first  appearance 

of  the  disk.    a.  Mouth  in  the  midst  of  the  four-pronged  ejecting    all    their    in~ 
proboscis.  £.  Stomach,  c.  Echinoid  disk,  dddd.fovit 

arms  of  the  Pluteus  body.     e.  Calcareous  frame-work,  temal  Organs,  SUTviv*- 
./".  Ciliated  lobes,     g  g  g  g.  Ciliated  processes  of  the  .  ,«         i  /•  «i 
proboscis.     B.   Disk,  with   the  first  indication  of  the  lng   tne   1OSS   Ol    tnCSC 
cirrhi.     C.  Disk,  with  the  origin  of  the  spines  between  ~oH-c       otirl    aff/^r«ro,-r1 
the  cirrhi.     D.  More  advanced  disk,  with  the  cirrhi  PartS>     a!K 
and  spines  projecting  considerably  from  the   surface.  t*pr>T"OflllcinP"          I'll  PIT! 
(N.B.  In  figs.  B,  C,  and  D,  the  Pluteus  is  not  repre- 
sented, its  parts  having  undergone  no  change,  save  in  Their  Vermiform    lar- 
becoming  relatively  smaller.) 

va  has  no  skeleton. 

6.  The  Radiate  type  of  animal  life  well  illustrates  the 
intellectual  plan,  or  typical  design,  of  living  forms,  and 


RADIATA.  191 

contains  many  instances  totally  unaccountable  on  any 
scheme  of  material  gradation  whatever.  The  nettling 
thread-cells,  or  Cnidce  in  the  Hydroids,  the  peculiar  alter- 
nation of  generations  in  the  Medusae,  the  great  amount 
of  muscular  development  in  the  Crinoida,  the  pedicel- 
lariae,  and  the  dental  apparatus  of  Echinus,  are  all  exam- 
ples of  structural  arrangement  for  a  purpose,  and  make 
against  the  theory  of  evolutional  development,  or  sur- 
vival of  the  fittest.  Each  of  these  structures  are  the 
most  perfect  of  their  kind,  and  seem  to  have  no  previous 
structure  from  which  they  have  developed,  as  they  have 
left  no  succeeding  apparatus  analogous  or  homologous 
to  them. 


1 92  THE  SCIENCE  OF  LIFE. 


CHAPTER   XIII. 

MOLLUSCA. 

I  have  seen 

A  curious  child  applying  to  his  ear 
The  convolutions  of  a  smooth-lipped  shell, 
To  which,  in  silence  hushed,  his  very  soul 
Listened  intensely,  and  his  countenance  soon 
Brightened  with  joy  ;  for  murmuring  from  within 
Were  heard  sonorous  cadences  whereby, 
To  las  belief,  the  monitor  expressed 
Mysterious  union  with  its  native  sea. 

— WORDSWORTH. 

1.  THE  type  of  Mollusca,  or  soft-bodied  animals,  is  in- 
dicated by  the  name,  derjved  from  the  Latin  mollis,  soft. 
Like  other  types  it  embraces  species  of  various  degrees 
of  complexity  of  structure,  and  of  various  forms.     It  in- 
cludes soft-bodied,  unjointed  animals,  possessing  a  mus- 
cular skin,  or  mantle,  generally  protected  by  a  calcareous 
shell,  and  whose  nervous  system  is  scattered.     It  is  sub- 
divided into    i.   MOLLUSCOIDA,    containing  the  classes 
Polyzoa,  Tunicata,  and  Brachiopoda;  and  2.  TRUE  MOL- 
LUSCA,  embracing  the  classes  Lamellibranchiala,  Gaster- 
opoda, and  CepJialopoda. 

2.  POLYZOA  (Gr.  polus,  many,  and  zoon,  animal)  derive 
their  name  from  the  fact  of  their  living  in  clusters  or 
colonies.     They  are  sometimes  called  Byozoa,  (Gr.  byon, 
moss,  and  20011,  animal,)  or  Sea-moss.     They  greatly  re- 
semble the  Hydroid  polyps,  but  from  the  greater  complex- 
ity and  character  of  their  organization  they  have  been 


MOLLUSCA. 


193 


removed  to  this  type.  The  cells  of  a  group  are  not  con- 
nected with  a  common  tube,  as  in  Caelenterates,  and  each 
animal  possesses  a 
distinct  alimentary 
canal  and  nervous 
system.  Sometimes 
the  colonies  are  foli- 
aceous,  or  leaf-like, 
as  the  Sea  Mat, 
Flustra,  (Fig.  92,) 
and  at  others  plant- 
like,  as  the  Phimat-  FlG  92._SeaMati  (Flustra /oliacea.)  A.  Magnified. 

ella.  (Fig. 93.)  They  B-  Natural  size- 

sometimes  spread  over  rocks  and  sea-weeds  like  delicate 

lace-work,  and  the  majority  are  coral-making  animals,  or 


FlG.  93. — Plumatella.     a.  Natural  size.     b.  A  group  enlarged,     c.  Anal  orifice. 

secrete  carbonate  of  lime.     The  mouth  of  each  animal  is 
surrounded  by  ciliated  tentacles  which  serve  for  prehen- 


194  THE  SCIENCE  OF  LIFE. 

sion,  circulation,  and  respiration.  Many  species  are  fur- 
nished with  organs  of  a  remarkable  and  peculiar  kind, 
called  Avicularia,  (avicula,  a  little  bird,)  or  "  bird's 
heads,"  which  during  life,  and  even  after  the  death  of 
the  animal,  keep  up  a  continual  motion,  see-sawing,  and 
snapping,  and  opening  their  jaws  in  the  most  singular 
manner.  Their  use  is  unknown,  but  Mr.  Gosse  conject- 
ures that  they  may  seize  and  hold  minute  animals  until 
decomposition  attracts  a  crowd  of  Infusoria,  which  may 
serve  the  Polyzoan  for  food.  Some  species  of  Polyzoa 
are  found  in  fresh  water. 

3.  TUNICATA,  named  from  the  Latin  tunica,  a  cloak, 
is  a  class  of  Molluscoida  which  are  enveloped  in  a  tough, 
leathery  sac,  or  "  test."  This  sac  is  double-walled,  but 
not  capable  of  protrusion.  The  mouth  of  the  animal 
opens  into  the  bottom  of  a  respiratory  sac  whose  walls 
are  lined  by  a  net-work  of  blood-vessels.  The  tubular 
heart  exhibits  the  curious  phenomenon  of  reversing  its 
action  at  brief  intervals,  so  that  the  blood  oscillates 
backward  and  forward  in  the  same  vessels.  The  wall  of 
the  tunic  contains  cellulose,  which  is  generally  a  vege- 
table product. 

These  bottle-shaped  creatures  are  found  in  the  ocean, 
"  solitary,"  attached  to  rocks  or  sea-weed,  and  often 
glued  together  in  bunches.  Sometimes  they  are  in  "  so- 
cial "  groups,  as  in  Fig.  94,  or  "  compound,"  as  Fig.  95. 

The  Salpce  are  free  swimming,  transparent  Ascidians, 
(askos,  a  bag ;  eidos,  like,)  or  Tunicates,  often  found  ad- 
hering to  each  other  in  long  chains,  which  give  birth  to 
solitary  individuals  of  different  form  by  alternation  of 
generations. 


MOLLUSCA. 


195 


Young  Tunicata  swim,  like  tadpoles,  by  a  tail,  which 
contains  a  peculiar  rod-like  body,  consisting  of  nucleated 


FIG.  94. — A.  Group  of  Perophora,  (enlarged,)  growing  from  a  common  stalk  : — B.  Sin- 
gle Perophora.  a.  Test.  b.  Inner  sac.  c.  Branchial  sac,  attached  to  the  inner  sac 
along  the  line  c' .  c' .  e.  e.  Finger-like  processes  projecting  inward,  f.  Cavity  between 
test  and  internal  coat,  f .  Anal  orifice  or  funnel,  g.  Oral  orifice,  g* '.  Oral  tentacula. 
h.  Downward  stream  of  food,  h' '.  OZsophagus.  i.  Stomach,  k.  Vent.  /.  Ovary.  (?) 
n.  Vessels  connecting  the  circulation  in  the  body  with  that  in  the  stalk. 


FIG.  95. — Botryllus  violaceus  :    A.  Cluster  on   the  surface  of  a  Fucus.     B.  Portion  of 
the  same  enlarged. 

cells  like  the  chorda  dorsalis,  or  notochord ;  an  elongated 
mass  of  cells  in  the  Vertebrate  embryo,  which  is  after- 


196  THE  SCIENCE  OF  LIFE. 

ward  replaced  by  the  vertebral  column.  From  this  re- 
semblance the  partisans  of  evolution  have  claimed  that 
this  simple  cellular  structure  is  the  prototype  of  that 
which  distinguishes  the  higher  animals,  and  that  from 
the  simple  Ascidian  the  Vertebrate  has  been  developed. 
Such  foreshadowings  of  higher  types  is  not  uncommon. 
It  will  require,  however,  much  greater  evidence  to  prove 
transmutation  than  such  resemblances. 

4.  BRACHIOPODA   are   protected   by  a  bivalve  shell, 
which  is  lined  by  an  expansion  of  the  integument,  or 
"  mantle."     The  valves  of  the  shell  are  applied  to  the 
dorsal  and  ventral  sides  of  the  body.     The  ventral  valve 
is  usually  larger  and  more  convex  than  the  other ;  but 
they  are  symmetrical,  that  is,  a  vertical  line  from  the 
hinge  divides  the  shell  into  equal  parts.     The  ventral 
valve  generally  has  a  hole,  or  foramen,  through  which  a 
fleshy  foot  protrudes  for  attachment.      The  mouth  is 
furnished  with  two  long  arms,  fringed  with  cirri,  gener- 
ally coiled  up  and  supported  by  a  bony  frame-work  in 
the  shell — the   "  carriage-spring  apparatus."     As  there 
are  no  gills,  the  animal  respires  by  the  arms  or  the  man- 
tle.     Brachiopods  were  once  very  abundant,  over  two 
thousand  extinct   species   having  been  described ;    but 
less  than  one  hundred  species  are  now  living. 

In  all  the  Molluscoida  the  nervous  system  consists  of 
a  single  ganglion,  or  of  a  principal  pair  with  accessory 
ganglia  placed  between  the  oral  and  anal  apertures,  or 
on  the  ventral  surface  of  the  body.  Some  naturalists 
connect  them  with  the  Worms. 

5.  LAMELLIBRANCHIATA  (Lat.,  lamella,  a  plate ;   Gr., 
bragchia,  gill)   comprise   the   ordinary  bivalves,   as   the 


MOLLUSCA.  197 

Oyster,  Mussel,  and  Clam,  and  are  characterized  by  the 
possession  of  lamellar  gills.  The  shells  differ  from  those 
of  Brachiopods  in  being  placed  on  the  right  and  left  sides 
of  the  body,  so  that  the  hinge  is  on  the  back  of  the  ani- 
mal, and  in  being  generally  unequilateral  and  equivalved. 
They  are  sometimes  termed  CONCHIFERA,  or  shell-fish, 
(Lat.,  concha,  a  shell ;  fero,  I  carry.) 

The  shells  of  Mollusks  are  epidermal  structures.  The 
mantle,  or  loose  skin,  secretes  calcareous  matter  in.  lay- 
ers, converting  the  epidermis  into  shell.  The  micro- 
scopic structure  is  so  characteristic  that  a  thin  section  of 
a  fragment  often  suffices  to  determine  the  group  to  which 
it  belongs.  A  large  class  of  shells  is  formed  like  the 
Oyster,  of  three  parts;  the  external  epidermis,  brown 
and  of  a  horny  texture  ;  the  prismatic  portion,  consist- 
ing of  minute  columns  set  perpendicularly  to  the  surface ; 
and  the  internal  nacreous,  or  pearly  layer,  made  up  of 
very  thin  plates  whose  edges  overlap  and  form  wavy 
lines.  In  many  cases  the  prismatic  and  pearly  layers 
are  traversed  by  minute  tubes.  The  pearls  of  commerce, 
found  in  the  mantle  of  some  Mollusks,  are  similar  in 
structure  to  the  shell ;  but  what  is  the  innermost  layer 
in  the  shell  is  outside  and  much  finer  in  the  pearl,  which 
is  formed  around  some  nucleus,  as  an  organic  particle 
or  grain  of  sand. 

Shells  of  one  piece  are  called  "  univalves,"  as  the  snail. 
Others,  as  the  Clam,  are  of  two  parts,  and  are  called 
"  bivalves."  The  ribs,  ridges,  and  spines  on  the  outside 
mark  successive  periods  of  growth,  and  correspond  with 
the  age  of  the  animal.  Figs.  96  and  97  show  the  princi- 
pal parts  of  ordinary  bivalves  and  univalves.  The  valves 
17* 


198 


THE  SCIENCE  OF  LIFE. 


of  a  bivalve  are  generally  equal,  except  in  Brachiopods 
and  in  the  Oyster.  The  umbones,  or  beaks,  are  a  little 
in  front  of  the  center,  and  turn  toward  the  mouth  of  the 
animal.  The  valves  are  joined  by  a  ligament  near  the 


FlG.  96. — a.  b.  Length  of  the  shell,     c.  d.  Height,    e.  Lunula,  above  which  is  the  sum- 
mit,   d.  The  ventral  or  inferior  edge. 


A  B 

FIG.  97. — A.  The  line  across  marks  the  thickness  of  bivalves.  B.  a.  Anterior  extrem- 
ity, b.  Posterior,  c.  d.  Muscular  impressions,  e.  f.  Palleal  impression,  g.  Lower 
edge  of  the  left  valve. 

umbones,  and  often  also  by  a  "  hinge  "  formed  by  the 
"  teeth  "  of  one  valve  locking  into  cavities  of  the  other. 
The  aperture  of  a  univalve  is  sometimes  closed  by  a 
horny  or  calcareous  plate,  called  an  "  operculum" 


MOLLUSCA. 


199 


Lamellibranchs  breathe  by 
four  plate-like  gills,  two  on  each 
side,  underneath  the  mantle. 
(Fig.  98.)  In  the  higher  forms 
the  mantle  is  rolled  up  into  two 
tubes,  or  siphons,  for  the  inha- 
lation and  exhalation  of  water. 
The  mouth  opens  into  the  stom- 
ach, which  lies  imbedded  in  a 
large  liver,  and  the  intestine, 

FIG.  98. — Diagrammatic  Transverse 
after  a  few  turns,  passes  direct-    Section  of  Anodon,  through  the  heart. 

.  a.  a.  Lobes  of  mantle,   b.  b.  Gills,  show- 

ly   through  the  heart.     (Fig.  99.)     ing  transverse  partitions,   c.  Ventricle 
rr^i  •    ,          r     of  heart,   d.  d.  Auricles,    e.  Pericardi- 

The  nervous  system  consists  of   um  f  Glandular  sac  of  organ  of  Bo- 
three  pairs  of  ganglia,  and  the  Ja™5-    *  Vestibu1!;  or  middle  sac. 

h.  Venous  sinus,  k.  Foot.   A.  A.  Bran- 
heart  has  tWO'  Chambers,  an  aU-    chial  or  pallial  chamber.    B.  B.  Epi- 

branchial     chamber,     communicating 

ricle  and  ventricle,  and,  in  some  with  cloaca, 
cases,  two  auricles  and  a  ventricle.  The  ventricle  pro- 
pels the  blood  into  the  arteries,  by  which  it  is  distributed 
through  the  body.  From  the  arteries  it  passes  into  the 
veins,  and  is  conducted  to  the  gills,  where  it  is  aerated, 
and  is  finally  returned  to  the  auricles. 

A  few  Lamellibranchs  are  fixed,  as  the  Salt-water 
Mussel,  which  hangs  to  the  rocks  by  a  cord  of  threads 
called  "byssus,"  and  the  Oyster,  which  habitually  lies 
on  its  left  valve ;  but  the  rest  have  a  foot  by  which  they 
creep  about.  There  are  more  than  four  thousand  living 
species,  fresh  water  and  marine,  which  range  from  the 
line  of  shore  to  the  depth  of  a  thousand  feet. 

The  muscular  impressions  on  the  shell,  (c.  d.,  Fig.  97 ;) 
the  presence  of  a  pallial  sinus,  e.,  which  indicates  the 
possession  of  siphons  ;  the  structure  of  the  hinge,  and 


2oo  THE  SCIENCE  OF  LIFE. 

the  symmetry  of  the  valves,  are  the  chief  characters  for 
distinguishing  genera  and  species  of  this  class,  which 


FIG.  Q9. — Anatomy  of  a  bivalve  Mollusk,  (Mactra.)  «.  Shell-muscles,  b.  Ganglia. 
c.  Heart,  d.  Liver,  e.  Mouth,  f.  Labial  tentacles,  g.  Foot.  h.  Stomach.  /.Intestine. 
k.  Anus.  m.  Mantle,  n.  Branchiae,  o.  Base  of  inhalent  siphon.  /.  Base  of  exhalent 
siphon. 

has  been  divided  into  groups,  based  on  the  possession 
or  non-possession  of  siphons,  as  follows : 

Section  A.  Asiphonidce.  Without  respiratory  siphons, 
so  that  the  shell  shows  the  pallial  line  simple,  and  not 
indented.  As  in  the  families  of  Oysters,  (Ostreid&l) 


MOLLUSCA.  201 

Mussels,  (Mytilidcs^)  Wing-shells,  or  Pearl  Oysters,  (Av- 
iculid&l}  and  River  Mussels,  (Unionidcs^} 

Section  B.    Siphonida.    Having  siphons. 

(i.)  Integro-pallialia.  Siphon  short,  pallial  line  sim- 
ple, as  in  the  families  Tridacnidce,  Cardiadce,  (Cockles,) 
and  Cyprinidce,  (Heart-cockles.) 

(2.)  Sinu-pallialia.  Long  siphons,  pallial  line  sinu- 
ated,  as  in  Venerida,  (Clams,)  Mactridcz,  Solenidce,  (Ra- 
zor-shells,) and  Pholadidce,  (Boring-shells.) 

6.  GASTEROPODA,  (Gr.,  gaster,  stomach  ;  pous,  foot.) 
This  class  derives  its  name  from  the  fact  that  loco- 
motion is  usually  effected  by  a  muscular  expansion 
of  the  under  surface  of  the  body,  termed  the  "  foot." 
It  includes  all  the  univalve  shells,  the  naked  slugs,  the 
Dorsibranchs,  the  Pteropods,  and  the  Multivalvular 
Chiton. 

The  body  of  most  Gasteropods  is  unsymmetrical,  the 
organs  not  being  in  pairs,  but  single,  and  on  one  side, 
instead  of  central.  The  mantle  is  continuous  round  the 
body,  not  bilobed,  as  in  Lamellibranchs.  A  few,  as  the 
Garden-snail,  have  a  lung,  but  the  majority  breathe  by 
gills.  The  head  is  more  or  less  distinct,  and  is  provided 
with  two  tentacles,  with  auditory  sacs,  or  rudimentary 
organs  of  hearing  at  their  bases.  The  eyes  are  some- 
times quite  conspicuous.  The  Snail,  for  example,  carries 
two  ocelli,  or  simple  eyes,  on  the  tip  of  its  long  tentacles. 
Each  consists  of  a  globular  lens,  of  short  focus,  which  is 
a  part  of  the  transparent  cornea,  with  a  colored  mem- 
brane (choroid)  and  a  nervous  net-work  (retina)  behind. 
The  arrangement  for  retracting  the  eye  and  tentacle  is 
seen  in  Fig.  100. 


202 


THE  SCIENCE  OF  LIFE. 


The  mouth  of  Gasteropods  possesses  a  peculiar  strap- 
like  organ,  the  odonto- 
phore,  (pdous,  tooth ;  phero, 
I  bear.)  It  is  studded  with 
three  or  more  rows  of  lin- 
gual teeth,  formed  of  sili- 
ca, which  are  the  serrated 
edges  of  minute  plates,  the 
number  of  which  varies  in 
different  species;  the  gar- 
den Slug  has  one  hundred 
rows  with  one  hundred 

o«/-J     <»irrV»4"tr     f*a<»fVi     in     e*ir\\ 

FIG.  too.— 

structure  of  tentacles:   a.  Right  inferior  ten-     j-QW.   (Fig".  IOI.)    The  Strap 
tacle  retracted  within  the  body.    b.  Right  su-  '   \       S*  V 

perior  tentacle  fully  protruded,  c.  Left  superior     or  "  tOngUC,"   playS  OVCr  3. 
tentacle  partially  inverted,    d.  Left   inferior 

tentacle.   /.  Optic  nerve,    g.  Retractor  mus-     CartilaginOUS      Cushion,     Of 
cle.    k.  Optic  nerve  in  loose  folds.   /.Retractor  .  .        .   .       , 

muscle  of  head.    *.  Nerve  and  muscle  of  left     pulley,  Connected  With  the 

lower  jaw,  and  the  teeth 
are  renewed  by  fresh  growths 
from  the  membrane  beneath. 
The  gullet  is  long,  and  frequent- 
ly expands  into  a  crop  ;  the 
stomach  is  often  doable,  the  an- 
terior being  a  gizzard  provided 
with  teeth  for  mastication  ;  the 
intestine  passes  through  the  liv- 
er, and  ends  in  the  fore  part  of 
the  body,  usually  on  the  right 
side.  The  heart  is  double,  and 
FIG.  loi.— Palate  of  Buccinum  a  capillary  system  intervenes  be- 

undatum,  as  seen  under  polarized 

light.  tween  the  arteries  and  veins,  but 


inferior  tentacle.    /.  m.  Nervous  collar. 


MOLLUSCA.  203 

the  liver  does  not  possess  a  distinct  portal  system,  as  in 
Vertebrates.    (Fig.  102.) 


FIG.  102. — Anatomy  of  Turbo  Pica :  /.  Foot.  o.  Operculum.  t.  Proboscis,  ta.  Tenta- 
cula.  y.  Eyes.  m.  Mantle  opened  longitudinally,  to  show  the  disposition  of  the  respira- 
tory cavity,  f.  Anterior  border  of  the  mantle,  which,  in  its  natural  position,  covers  the 
back  of  the  animal,  leaving  a  wide  slit  by  which  the  water  enters  the  branchial  cavity. 
b.  Gills,  vb.  Branchial  vein,  returning  to  the  heart,  c.  ab.  Branchial  artery,  a.  Anus, 
z.  Intestine,  e.  Stomach  and  liver,  ov.  Oviduct.  On  the  upper  side  of  the  neck  are  seen 
the  cephalic  ganglion,  and  the  salivary  glands ;  and  at  d.  is  shown  a  fringed  membrane, 
which  forms  the  lower  border  of  the  left  side  of  the  opening  that  leads  to  tne  respiratory 
cavities. 

The  univalve  shell  is  generally  a  coiled  tube,  wound 
round  a  central  axis,  or  columella;  the  nucleus,  or  earli- 
est part  of  the  shell  being  at  the  apex,  and  the  portion 
last  formed  being  the  open  mouth  at  the  lower  part,  01 
base.  The  direction  of  the  coil  may  be  concentric,  form- 
ing  a  discoidal  shell,  as  Planorbis,  but  it  is  generally  a 
true  spiral.  The  mouth,  or  aperture,  of  the  shell  is  en- 
tire in  most  vegetable-feeding  Gasteropods,  and  notched 
or  produced  into  a  canal  for  the  siphons  in  the  carniv- 


204 


THE  SCIENCE  OF  LIFE. 


orous  species.  The  former  are  generally  land  and  fresh- 
water forms,  and  the  latter  all  marine. 

Gasteropods  comprise  three  fourths  of  all  living  Mol- 
lusks,  and  are  representatives  of  the  type. 

Omitting  a  few  rare  forms,  as  Dentalium  and  Carin- 
aria,  we  may  divide  the  class  into  the  following  orders : 

1.  Pteropods,  (Gr.,  pteron,  wing  ;  pous,  foot,)  which  are 
small  marine  floating  Mollusks,  whose  main  organs  re- 
semble a  pair  of  fins  or  wings,  whence  the  common  name, 
"  Sea-butterflies."      Many  have  a  delicate,  transparent 
shell.     The  head  is  said  to  carry  six  appendages,  armed 
with  several  hundred  thousand  suckers,  forming  a  pre- 
hensile apparatus  unequaled  in  complication. 

2.  Opisthobranchs,    (Gr.,    opisthon,    behind  ;    bragchia, 


FIG.  103.— A.  Tritonia  Hombergi.     B.  Horned  Doris. 

gills.)  These  are  generally  naked  Sea-slugs,  a  few  only 
having  a  small  shell.  The  feathery  gills  are  behind  the 
heart,  (whence  the  name.)  They  are  found  in  all  seas, 
generally  on  rocky  coasts.  When  disturbed,  most  of 
them  draw  themselves  up  into  a  lump  of  jelly  or  tough 
skin.  These  naked-gilled  Mollusks  (Niidibranchiatd)  ex- 


MOLLUSCA. 


205 


hibit  a  great  diversity  of  form  and  a  variety  of  beautiful 
colors.  The  Sea-lemon,  (Doris,}  the  beautiful  Tritonia, 
(Fig.  103,)  the  painted  Eolis,  the  Sea-hare,  (Aplysia,) 
which  emits  a  violet  or  reddish  fluid  from  the  man- 
tle when  alarmed,  and 
the  Bubble-shell  (Bui- 
la)  are  examples. 

The  embryo  of  the 

naked-gilled  Mollusks      /V^l  /     I        t\ 
is  very   minute,    and 
resembles    a    Rotifer 

rather  than  a  Mollusk.     FlG"  '^-Embryos  of  Nudibranchiate  Gasteropods. 

It  is  inclosed   in  a  transparent  nautilus-like  shell,  pro- 
vided with  an  operculum.     (Fig.  104.) 


FIG.  105. — Snails  and  Slugs. 


3.  Pulmonates  (having  lungs)  are  air-breathing  Gaster- 
opods, represented  by  the  common  Snail.     They  have 
18 


206 


THE  SCIENCE  OF  LIFE. 


the  simplest  form  of  lung — a  cavity  lined  with  a  delicate 
net-work  of  blood-vessels,  which  opens  externally  on  the 
right  side  of  the  neck.  This  opening  is  covered  by  a 
valve.  They  are  found  in  all  zones,  but  most  where  lime 
and  moisture  abound.  All  feed  on  vegetable  matter.  A 
few  are  naked,  as  the  Slug ;  some  are  terrestrial ;  oth- 
ers live  in  fresh  water.  The  Land-snails,  as  the  Helix, 
Bulimus,  and  Limax,  (Slug,)  have  four  horns,  the  short 
front  pair  being  the  true  tentacles,  and  the  long  hinder 
pair  the  telescopic  eyes.  The  Pond-snails,  as  Limnaa 
and  Planorbis,  have  no  eye-stalks,  the  eyes  being  at  the 
base  of  the  tentacles.  They  are  obliged  to  come  to  the 
surface  of  the  water  to  breathe.  (Fig.  105.) 


FIG.  106. — Chiton. 


FIG.  107.— Fissurella  Reticulata. 


4.  Prosobranclis. 
(Gr.^proson,  before 


Having  gills  in  front  of  the  heart. 
bragchia,  a  gill.)  These  are  aquatic 
and  generally  marine  animals,  the 
most  highly  organized  and  most 
abundant  of  all  the  Gasteropods. 

Among  the  lower  forms  ate  the 
singular  Chiton,  (Fig.  106,)  covered 
with  eight  shelly  plates  ;  Limpet,  (Pa- 
tella^]  well  known  to  every  sea-side 
visitor ;  and  the  beautiful  Ear-shell  Abalone,  (Haliotis^) 
(Fig.  108,)  often  used  for  ornamental  work  and  jewelry. 


FIG.  108.— Ear-shell,  or 
Haliotis.    Reduced. 


MOLLUSCA. 


207 


In  the  higher  Prosobranchs  the  gills  are  comb-shaped 
and  the  sexes  are  distinct.  The  group  includes  all  the 
spiral  univalve  sea-shells  and  a  few  fresh-water  shells. 
Many  have  the  aperture  entire,  as  the  fresh -water 
Paludina,  the  pyramidal  Trochus,  pearly  Turbo,  and 


FIG.  109. — The  Wentle-trap,  (Scalana.) 


FIG.  no. — Volute  Crawling. 


FIG.  in. — Murex. 


common  Periwinkle  (Littorind]  from  the  sea.  Others, 
the  highest  of  the  race,  have  the  margin  of  the  aper- 
ture notched  or  produced  into  a  canal,  and  are  carniv- 
orous and  marine  ;  such  are  nearly  all  the  more  beauti- 
ful sea-shells,  as  the  Cowry  (Cyprced]  Volute,  (Fig.  1 10,) 


208 


THE  SCIENCE  OF  LIFE. 


Olive,  Cone,  Harp,  Murex,  (Fig.  in,)  Whelk,  (Fig.  112,) 
and  Winged-shell,  (Fig.  113.) 


FlG.  112. — The  Whelk,  (Bitccinuui,)  showing  its  operculum. 

7.  CEPHALOPODA,  (Gr.,  cephalc,  head  ;  pous,  foot.)   The 

class  of  Cephalopods  stands 
at  the  head  of  the  Molluscan 
type.  Some  of  its  forms  sur- 
pass in  complexity  of  struct- 
ure the  highest  Articulates, 
although  not  so  representa- 
tive of  their  type  as  the  Gas- 
teropods.  They  are  aquat- 
ic free-swimming  or  creeping 
Mollusks,  inclosed  in  a  mus- 
\LL--y  cular  mantle,  and  in  some 

.  113. — Strombus  gigas,  or      Winged- 
shell  ;"  one  fifth  natural  size.    West  Indies.     spCClCS       having      a      Univalve 

shell.     The  foot  is  divided  into  eight  or  ten  long,  wav- 
ing, but  strong  tentacles,  bearing  numerous  suckers,  or 


MOLLUSCA. 


209 


acetabula.  The  adhesion  of  these  suckers  is  so  great 
that  it  is  easier  to  tear  away  a  limb  than  to  detach  it. 
Their  mechanism  may  be  understood  from  Fig.  1 14. 
The  mouth  has  a  horny  beak,  like  a  parrot's  bill,  but  the 
jaws  do  not  move  vertically,  like  the  bird's.  A  long 
gullet  ends  in  a  muscular  gizzard,  resembling  that  of  a 
fowl.  Below  this  is  a  cavity,  the  stomach  or  duodenum, 


FIG.  114. — Suckers  on  the  Tenta- 
cles of  a  Cuttle-fish  :  a.  Hollow  axis 
of  the  arm,  containing  nerve  and  ar- 
tery, c.  Cellular  tissue,  d.  Radi- 
ating fibers,  h.  Raised  margin  of 
the  disk  around  the  aperture  f,  g^ 
which  contains  a  retractile  mem- 
brane, or  "  piston,"  z". 


FIG.  115.  —  Morphology  of 
Cephalopoda.  Sepia  oflkina- 
hs,  laid  open  to  show  viscera, 
etc.  a.  Foot.  b.  Horny  jaws. 
c.  Principal  ganglion,  d.  Sal- 
ivary gland,  e.  OZsophagus. 
f.  Liver,  g.  Stomach,  h.  Py- 
loric  caecum.  i.  Ink  bag. 
k.  Ovary.  /.  Aperture  of 
atrial  system,  m.  Branchiae. 
n.  Oviduct,  o.  Cuttle-bone. 


which  receives  the  bile  from  a  large  liver.  The  intes- 
tine is  a  tube  of  uniform  size,  which,  after  one  or  two 
slight  curves,  bends  up,  and  opens  into  the  "  funnel " 
near  the  mouth.  (Fig.  115.)  The  head  is  set  off  from 
the  body  by  a  slight  constriction,  and  is  furnished  with 

a  pair  of  large,  staring  eyes,  which  are  constructed  like 

18* 


210  THE  SCIENCE  OF  LIFE. 

the  eyes  of  Vertebrates,  except  that  there  is  no  aqueous 
humor,  and  the  lens,  which  is  double,  is  bathed  freely 
by  the  water  in  which  the  animals  swim.  The  nervous 
system  is  more  concentrated  than  in  other  Invertebrates  ; 
the  cerebral  ganglia  are  even  inclosed  in  a  cartilaginous 
cranium.  All  the  five  senses  are  present.  The  integu- 
ment contains  pigment  sacs,  or  chromatophores,  which 
sometimes  tint  the  animal  with  variegated  colors.  It  is 
probable  that  they  in  some  way  subserve  the  sense  of 
sight,  as  the  animal  swims  with  its  head  backward. 
Some  Cephalopods  have  an  internal  shell,  secreted  by  a 
fold  of  the  mantle,  called  the  "  cuttle-bone"  or  "  pen." 

Two  or  four  pairs  of  plume-like  gills  are  situated  in 
the  pallial  cavity,  into  which  the  sea-water  is  admitted 
at  one  end  and  expelled  through  the  funnel  at  the  other 
by  muscular  contraction.  These  contractions  serve  both 
for  respiration  and  locomotion,  the  pressure  of  the  ex- 
pelled water  driving  the  animal  in  an  opposite  direction. 
The  systemic  heart  pumps  the  blood  all  over  the  body, 
which  then  returns  through  capillaries  into  veins  which 
conduct  the  blood  back  to  the  gills,  where  it  is  purified, 
and  whence  it  is  propelled  to  the  heart  by  contractile 
sacs,  called  branchial  hearts,  placed  at  the  base  of  each 
gill.  In  addition  to  other  viscera,  a  large  secreting  sac, 
the  ink-bag,  is  often  present,  containing  a  dark  fluid 
which  the  animal  ejects  at  will  through  a  duct  opening 
at  the  base  of  the  funnel.  The  sexes  are  always  distinct. 
During  reproduction  the  spermatozoa  are  temporarily 
transferred  to  one  of  the  arms,  which  becomes  curiously 
altered  and  unfit  for  locomotion  ;  in  this  condition  it  i« 
said  to  be  hectocotylized. 


MOLLUSCA. 


211 


I.)  Tetrabranchs.  This  order  has  four  gills,  forty  or 
more  short  tentacles,  and  an  external  chambered  shell. 
The  partitions  of  the  shell  are  united  by  a  tube,  called  a 
siphuncle,  and  the  animal  lives  in  the  last  and  largest 
chamber.  These  chambered  shells  were  once  very  abun- 
dant. More  than  two  thousand  fossil  species  are  known, 
among  which  are  the  Nautilus,  Ammonite,  and  Ortho- 
ceros.  They  have  but  one  living  representative — the 
Pearly  Nautilus.  This  straggler  of  a  mighty  race  dwells 
at  the  bottom  of  the  Indian  Ocean.  The  shell  is  well 
known,  but  only  two  or  three  specimens  of  the  animal 
have  been  obtained. 

2.)  Dibranchs.  Those  having  two  gills.  They  are  the 
most  active  of  Mollusks,  and  the  tyrants  of  the  lower 


FIG.  116.— The  Paper  Nautilus,  (Argonauta  Argo.)  Fig.  i.  Swimming  toward  the 
point  a.  2.  Walking  on  the  bottom.  3.  Contracted  within  its  shell,  which  is  partly 
embraced  by  the  arms. 

tribes.  There  are  Cuttle-fish  and  Poulps  (or  Devil-fish) 
so  large  as  even  to  be  dangerous  to  a  man  who  might  be 
swimming  near  them,  and  the  stories  of  novelists  like 


212 


THE  SCIENCE  OF  LIFE. 


Victor  Hugo  have  some  foundation  in  the  large  size  and 
repulsive  aspect  of  these  creatures.  They  crawl  with 
their  arms  on  the  bottom  of  the  sea,  head  downward, 
and  also  swim  backward  or  forward,  usually  with  the 
back  downward,  by  means  of  fins,  or  squirt  themselves 
backward  by  forcing  water  through  their  funnels. 

The  Paper  Nautilus  (Argonaut  a)  (Fig.  116)  and  the 
Poulp  have  eight  arms.  The  Squid  (Loligo)  and  Cuttle- 
fish (Fig.  117)  have  ten  arms,  the  additional  pair  being 


FIG.  117. — Cuttle-fish. 


longer  than  the  others.  Their  eyes  are  movable,  while 
those  of  the  Argonaut  and  Poulp  are  fixed.  The  Squid, 
used  for  bait  by  cod-fishermen,  has  an  internal  horny 
"  pen,"  and  the  Cuttle  has  a  spongy,  calcareous  bone. 


ARTICULATA.  213 


CHAPTER  XIV. 

ARTICULATA. 

"  Yet  wert  thou  once  a  worm — a  thing  that  crept 
On  the  bare  earth,  then  wrought  a  tomb,  and  slept ! 
And  such  is  man  ;  soon  from  his  cell  of  clay 
To  burst  a  seraph  in  the  blaze  of  day  !  " — ROGERS. 

I.  THE  Articulated  type  of  animals  (Lat.,  articulus,  a 
joint)  includes  all  which  possess  a  distinctly  jointed 
body,  as  Worms,  Crustacea,  and  Insects.  It  contains  a 
greater  number  and  variety  of  forms  than  all  the  other 
types  put  together.  The  nervous  system  consists  chiefly 
of  a  double  chain  of  ganglia  along  the  ventral  surface  of 
the  abdomen,  connected  together  by  nerve-filaments. 
The  part  representing  the  brain  is  in  the  form  of  a  ring 
encircling  the  gullet.  The  circulatory  apparatus  is  a 
tubular  structure  running  along  the  back,  and  communi- 
cating with  the  body-cavity.  The  limbs,  when  present, 
are  jointed  and  hollow,  and  on  the  same  side  as  the 
nerve-cords. 

There  are  five  classes  of  Articulates :  the  aquatic 
Worms  and  Crustaceans,  and  the  air-breathing  Spiders, 
Myriapods,  and  Insects.  It  must  be  remembered,  in 
accordance  with  the  principles  so  often  referred  to  in  the 
present  work,  that  the  order  of  classes  in  a  type  is  one 
of  relation  rather  than  of  structural  rank.  Classes  can- 
not be  arranged  serially,  any  more  than  species,  as  if  one 
was  an  improvement  on  another,  by  progressive  devel- 


214  THE  SCIENCE  OF  LIFE. 

opment.  In  many  respects  Myriapods  are  like  Worms, 
yet  their  heads  show  a  resemblance  to  Insects.  Some 
Spiders  are  less  complicate  than  Myriapods,  yet  for  their 
wonderful  instincts  Owen  places  them  above  Insects. 
Insects  begin  life  as  worm-like  embryos.  Classes  in  the 
articulate  type  depend  on  the  equal  or  unequal  develop- 
ment of  the  body-segments,  and  the  number  and  form 
of  appendages.  Articulates  with  jointed  appendages 
articulated  to  the  body  are  called  Arthropoda,  (Gr.,  art/i- 
ron, a  joint ;  podes,  feet.) 

2.  The  class  of  WORMS,  called,  also,  Annelida,  or  An- 
nulata,  (Annulus,  a  little  ring,)  includes  animals  with  a 
soft  skin  and  a  body  formed  of  a  succession  of  rings,  or 
movable  joints.  They  differ  from  the  Anthropoda  in 
not  having  jointed  limbs.  A  water-vascular  system  ex- 
ists, but  it  has  no  connection  with  locomotion.  The 
blood  is  often  reddish,  but  the  color  does  not  depend  on 
colored  corpuscles,  as  in  vertebrates.  The  circulatory 
apparatus  is  more  highly  developed  than  in  Insects. 

Some  worms  can  only  live  as  parasites  upon  the  blood 
or  juices  of  other  animals,  and  in  these  the  circulatory, 
water-vascular,  and  digestive  systems  become  rudiment- 
al,  the  nervous  system  is  undeveloped,  the  body-cavity 
often  vanishes,  and  the  reproductive  organs  alone  are 
fully  represented. 

Order  i.  Tceniada ;  (tcenia,  a  tape.)  Tape-worms,  so 
called  from  their  length  and  flatness.  They  live  chiefly 
in  the  digestive  canal  of  higher  animals.  Three  species 
are  occasionally  parasitic  in  man.  The  head,  which  is 
the  true  animal,  is  provided  with  hooks  or  suckers,  by 
which  it  adheres  to  the  mucous  membrane  of  its  host. 


ARTICULATA. 


215 


It  feeds  by  imbibition,  (osmosis,}  there  being  no  mouth 
or  alimentary  canal.  The  joints,  or  segments,  are  called 
proglottides,  (singular,  proglottis^}  and  are  but  successive 
growths  containing  ova.  The  life-history  of  these  worms 
is  a  curious  instance  of  alternation  of  generations.  The 
fertilized  ova  are  set  free  by  the  decomposition  of  the 
joint,  or  proglottis.  They  are  then  swallowed  by  some 
animal,  and  the  tough  capsule  is  dissolved,  setting  free 
the  embryo,  which  travels  through  the  tissues  of  its  host 
as  a  little  oval  body,  bearing  weak,  hook-like,  or  boring 
spines.  On  reaching  a  suitable  site,  as  the  liver,  it  an- 
chors, and  the  body  dilates  into  a  cyst,  or  sac  full  of 
water,  (Cysticercus^)  Many  animals,  formerly  known  as 
cystic  worms,  have  been  found  to  be  but  transitional 
stages  of  Taeniae.  In  this  condition  the  animal  may 


FIG.  118.  —  Morphology  of  Taeniada.  a.  Ovum  with  contained  embryo,  b.  Cysticercus 
longicollis.  c.  Head  of  Tsenia  solium,  (enlarged  ;)  the  circlet  of  hooklets  is  at  the  top, 
and  below  them  are  those  of  the  cephalic  suckers,  d,  A  single  segment  or  proglottis 
magnified,  i.  Generating  pore.  2.  Water  vessels.  3.  Dentritic  ovary,  e.  Portion  of 
Tape-worm,  natural  size,  showing  the  alternating  arrangement  of  the  generative  pores. 

remain  a  long  while  and  generate  new  cysts  by  budding, 
but  when  the  flesh  containing  the  "  scolex,"  or  resting- 
larva,  is  eaten  by  some  other  animal,  the  outer  wall  of  the 
cyst  dissolves,  and  becomes  a  true  Tape-worm.  The  hu- 
man Tape-worm  has  its  cystic  stage  in  "  measly"  pork, 


Of 


HIE  SCIENCE  OF  LIFE. 


while  the  Tape-worm  of  the  dog  develops  from  cysts 
found  in  the  hare,  and  that  of  the  cat  from  cysts  in  the 
mouse  ;  most  cases  requiring  two  animals  as  hosts  for 
perfecting  the  growth  of  the  worm.  (Fig.  1  18.) 

Order  2.  Trematoda  ;  the  Flukes.  (Gr.,  trema,  a  hole.) 
These  are  flat  or  roundish  parasitic  worms.  The  intes- 
tine is  branched,  and,  as  in  Coelenterata,  there  is  but  a 
single  opening,  which  serves  for  both  mouth  and  anus. 
There  are  suckers  at  the  anterior  end  of  the  disk.  They 

are  met  with  sometimes  in 
the  liver  of  the  sheep. 
•Order  3.  Turbellaria. 
These  are  non-  parasitic, 
and  may  be  found  on  the 
sea-shore,  under  stones,  or 
in  fresh-water  pools,  or  on 
moist  ground.  They  are 
small,  ciliated,  and  flat 
worms,  which  glide  with  a 
slug-like  motion  over  wet 
surfaces,  or  swim  by  the 
vibrations  of  their  cilia. 
In  the  small  flat  Plana- 
rians  the  digestive  cavity 
is  greatly  branched.  (Fig 
1  19.)  In  others  it  is  a  sim- 


II9.-Structure of  Polycelis  levigatus, 
(Planarian  worm.) 


ple  pouch,  with  no 

^  °rifice'        In   the 
forms  It  is  elongated.    Some 

of  the  largest  (the  Nemerteans]  are  like  long  ribbons; 
sometimes,  as  in  Borlasia,  being  twelve  feet  long. 


ARTICULATA.  21? 

Order  4.  Acanthocephala ;  (akantha,  a  thorn;  cephale, 
head,)  are  rounded,  parasitic  worms,  having  a  protrusible 
proboscis,  armed  with  recurved  hooks.  Their  structure 
is  not  unfrequently  as  simple  as  the  Protozoa,  having  no 
alimentary  canal  whatever,  and  subsisting  by  abrorption. 
Like  the  Tape-worms,  they  develop  through  an  alterna- 
tion of  generations. 

Order  5.  Gordiacece.  The  horse-hair-like  worm  found 
in  rain  pools  is  an  example  of  this  order.  It  begins  life 
as  a  little  larva  in  mud  or  water  pools.  By  means  of  its 
boring  spines  it  pierces  the  body  of  a  grasshopper,  bee- 
tle, or  other  insect,  where  it  becomes  encysted;  and 
grows  often  ten  times  as  long  as  its  host,  when  it  be- 
comes free  and  aquatic,  and  produces  its  eggs.  Some  of 
these,  as  the  Mermis  albicans,  multioly  so  rapidly  as  to 
give  rise  to  a  popular  belief  that  they  fall  as  "  worm- 
rains."  They  have  remarkable  tenacity  of  life,  as  they 
can  be  dried  into  brittle  threads,  and  yet  become  active 
on  being  moistened. 

Order  6.  Nematoidea,  (nema,  thread ;  eidos,  form.) 
Thread-worms,  or  round  worms.  These  are  both  free 
and  parasitic.  Some  of  them,  as  the  Ascaris  lumbticoi- 
desy  or  common  round  worm,  often  infests  the  small 
intestines  of  children,  while  the  Trichina  spiralis,  a  mi- 
nute worm  found  encysted  in  the  flesh  of  swine ,  when 
introduced  into  the  human  body,  multiplies  so  rapidly 
in  the  muscles  as  to  give  rise  to  dangerous,  and  even 
fatal  symptoms.  The  "  eels  "  in  vinegar  and  sour  paste 
also  belong  to  this  order. 

Order  7.  Rotifer  a,  or  Wheel  Animalcules.     These  are 

microscopic  in  size,  but  so  transparent  that  the  details 
19 


218 


THE  SCIENCE  OF  LIFE. 


of  organization  can  easily  be  seen.  The  male  rotifers 
are  few  and  small,  and  have  no  digestive  canal,  but  the 
females  have  a  complete  nutritive  system, 
and  many  species  are  provided  with  an  organ 
for  mastication  resembling  an  anvil  acted  on 
by  two  hammers,  another  instance  of  pecul- 
iarity of  structure  for  a  special  end.  These 
animals  are  capable  of  reviving  on  being 
moistened,  after  having  been  dried  up,  and 
that  many  times  in  succession.  (Fig.  120.) 

Order  8.  Gcpliyrca,  (gephura,  a  bridge,)  so 
called  in  allusion  to  the  apparent  connection 
which  they  exhibit  between  Echinoderms  and 
Articulates.       They    are    sometimes    called 
Spoon -worms,     Squirt -worms,    and    Siphon- 
worms,  (Sipunculus.)     They  have  all  the  as- 
pect  of   worms,   but   the   circle    of  tentacles 
FIG.  i2o.-Ro-  round  the  mouth  show  their  affinity  to  Ho- 
lothurians.     They  live  in  the   sand,  or  seek 
protection  in  some  empty  univalve  shell.     Their  elon- 
gated bodies  contain  a  long,  tortuous  intestine,  ciliated 
inside  and  outside.     They  have  no  locomotive  processes, 
nor  are  there  calcareous  or  silicious  spicules  in  their  skin. 
The  mouth  has  a  long  proboscis. 

Order  9.  Suctoria,  or  Leeches.  These  are  aquatic 
worms,  with  a  soft,  segmented  body,  provided  with  a 
suctorial  disk  at  one  or  both  ends.  The  mouth  of  the 
common  Leech  (Hirudo  medicinalis)  is  armed  with  three 
horny,  semi-lunar  plates,  with  finely  serrated  teeth,  which 
act  as  saws,  enabling  the  leech  to  make  incisions  in  the 
skin  of  its  host  through  which  to  suck  the  blood. 


ARTICULATA.  219 

Order  10.  Chcetopoda,  or  Bristle-footed  worms.  Some 
of  these  occur  under  the  stones  of  the  sea-shore,  as  the 
lug-bait  of  fishermen.  (Fig.  121.)  Others  se- 
crete a  glutinous  material  from  the  surface, 
which  cements  sand  and  other  foreign  bodies 
into  a  tube.  Others  secrete  calcareous  matter, 
which  forms  a  tubular  residence,  as  the  com- 
mon Serpula,  whose  white,  snake-like  concre- 
tions abound  on  the  stones  and  shells  of  the 
shore,  and  the  Spirorbis,  whose  minute  whorled 
shells  dot  the  surface  of  many  sea-weeds. 
Some  of  the  Nereids,  or  Sea-centipedes,  attain 
to  a  considerable  size,  one  species  being  four 
feet  long.  The  Sea-mouse  (Aphrodite]  also  be- 
longs to  this  order.  The  latter  is  clad  with 
iridescent  scales  and  bristles,  or  barbed  spines. 
Those  who  bear  the  gills  along  the  back  have 
been  called  Dorsibranchiates.  These  gills  are 
found  close  to  the  root  of  the  dorsal  oar,  or 
bristle,  and  the  blood  is  purified  by  being  ex- 

FlG.     121.   — 

posed  to  the  oxygen  held  in  solution  in  the  Lob-worm, 

r~,  i   •    1      1-  .  (Arenicola 

sea-water.  Those  worms  which  live  m  tubes 
(Tubicola)  have  the  gills  developed  only  on 
the  foremost  segments  of  the  body,  and  the 
dorsal  and  ventral  oars  of  the  other  joints  are  or  the  exje1r- 

J  nal  gills.   The 

rudimentary,  but  they  have  branching  tentacle-  large  head  is 

without    eyes 

like  processes  about  the  head.     In  Serpula  one  or  jaws. 
of  the  tentacles  is  formed  into  a  lid,  or  operculum,  with 
which  the  open  mouth  of  the  tube  can  be  closed  at  will. 
(Fig.  122.) 

The  common   Earth-worm   (Lum&rtcus)  has  few  and 


220 


THE  SCIENCE  OF  LIFE. 


small  bristles,  in  the  form  of  recurved  hooks  on  each 
ring  of  the  body,  which  assist  in  locomotion.  It  pos- 
sesses no  external  gills,  but  respires 
by  internal  ciliated  processes.  The 
nervous  system  is  often  but  little  de- 
veloped. The  mouth  is  on  the  second 
segment,  and  the  digestive  canal  is  a 
straight  tube,  which  is  wide,  and  al- 
ways full  of  earth,  which  these  animals 
devour  for  the  sake  of  the  organic  par- 
ticles contained  in  it ;  the  remaining 
part  being  cast  out  and  heaped  at  the 
outlet  of  their  burrows,  as  "  worm- 
casts."  For  better  division  of  the 
FIG.  ™.-serpuia.  material  swallowed  the  digestive  canal 
lias  a  muscular  gizzard  about  fifteen  rings  from  the 
mouth.  They  are  propagated  by  eggs. 

3.  The  class  of  CRUSTACEA,  (crusta,  a  crust  or  shell,) 
includes  all  Articulates  with  jointed  legs  and  gills.  They 
have  a  double,  or  complete  circulation  of  blood ;  a  dor- 
sal tube,  or  heart,  sending  off  a  system  of  arteries,  not 
found  in  insects;  but  the  blood,  as  it  leaves  these  tubes, 
escapes  into  the  general  cavity,  as  in  other  Articulates. 
(Fig.  123.)  The  shell,  or  carapace,  has  for  its  base  a 
horny  substance  called  Chitine.  It  is  also  found  in  the 
covering  of  Insects.  In  the  Crab  and  Lobster  there  is 
a  large  proportion  of  carbonate  of  lime  combined  with 
this,  rendering  the  carapace  extremely  hard.  In  others, 
a  mixture  of  chitine  and  albumen  gives  rise  to  a  softer 
integument.  The  rings  of  the  body  have  considerable 
freedom  of  motion,  by  means  of  striated  or  voluntary 


ARTICULATA.  221 

muscles.     The  normal  number  of  joints  is  twenty-one, 
but  two  or  three  are  often  blended.     To  each  of  these 


FIG.  123. — Circulating  Apparatus  of  Lobster :  a.  Heart.  3.  c.  Arteries  to  the  eyes 
and  antennae,  d.  Hepatic  artery,  e.f.  Arteries  to  thorax  and  abdomen,  gg.  Venous 
sinus.  Ji.  Gills,  z.  Branchial  veins. 

joints,  except  the  last,  there  is  attached  a  pair  of  mem- 
bers, the  forms  and  uses  of  which  vary  in  different  spe- 
cies, and  at  different  ages.  These  members  are  jointed, 
and  covered  with  a  similar  envelope,  or  crust,  to  that  of 
the  body.  As  the  body  grows  the  carapace  does  not 
grow  in  the  same  proportion,  rendering  frequent  molt- 
ings  necessary.  The  entire  covering  is  thrown  off  from 
body,  feet,  and  antennae  in  the  most  perfect  manner. 
The  Crustacea  differ  in  habits  as  well  as  in  structure. 
Most  live  in  the  water,  but  the  Land-crabs  inhabit  the 
land.  The  Hermit-crabs  (Pagurida)  live  in  the  empty 
shells  of  Mollusks,  which  they  seize,  often  killing  the  in- 
habitant. The  majority  of  Crustaceans  have  jaws  and 
organs  of  mastication,  but  some  have  no  such  organs, 
but  live  as  parasites,  especially  on  fishes,  sucking  their 
juices,  and  becoming  strangely  deteriorated.  The  ali- 
mentary canal  in  this  class  consists  of  a  short  gullet,  a 

gizzard-like  stomach,  and  a  straight  intestine.     Crusta- 
19* 


222 


THE  SCIENCE  OF  LIFE. 


ceans  pass  through  a  series  of  strange  metamorphoses 
before  reaching  their  adult  form.  The  Balanus,  or 
acorn-shell,  which  incrusts  the  rocks  of  the  sea-coast  in 
great  numbers,  begins  life  as  an  active,  one-eyed  free 
swimmer,  called  a  "  Nauplius"  which  after  one  or  two 
molts  becomes  a  pupa,  inclosed  in  a  bivalve  shell  by  a 
folding  of  the  dorsal  portion.  Finally  it  becomes  a  sed- 


FIG.  124. — Development  of  Balanus  balanoides  :  A.  Earliest  form.  B.  Larva  after 
second  molt.  C.  Side  view  of  the  same.  D.  Stage  immediately  preceding  the  loss  of 
activity,  a.  Stomach.  (?)  b.  Nucleus  of  future  attachment.  (?) 

entary  Cirripede,  (cirrus,  a  curl ;  pes,  a  foot.)  (Fig.  124.) 
It  will  be  convenient  to  divide  Crustaceans  into  four 
groups,  or  orders. 

I.)  Cirripeds,  distinguished  by  being  fixed,  having  a 
shelly  covering,  and  by  their  feathery  arms.  Such  are 
Barnacles,  (Lepas^)  which  have  a  peduncle,  or  stalk,  and 
are  often  found  on  the  backs  of  whales  or  on  ship's  bot- 
toms, and  Acorn-shells,  (Balanus^)  which  are  sessile. 


ARTICULATA. 


223 


2.)  Entomostracans,  which  have  a  horny  shell  and  no 
abdominal  limbs  ;  represented  by  the  little  Water-fleas, 
(Cyclops^  (Fig.  125,)  of 
our  ponds,  the  King- 
crabs  (Limulus]  and  the 
extinct  Trilobites.  The 
abdomen  of  the  King- 
crab  is  reduced  to  a 
mere  spine,  the  append- 
ages about  the  mouth 
are  used  for  locomo- 
tion, and  their  eyes  are 
smooth. 

3.)  Tetradecapods, 
small  fourteen  -  footed 
species  ;  as  the  Wood-louse,  or  Sow-bug,  (Oniscus?)  found 
in  damp  places,  and  the  Sand-flea,  (Gammarus,)  seen  in 
summer  on  the  sea-shore. 


FIG.  125. — Water-fleas  :    i.  Cyclops  communis. 
2.  Cypris  unifasciata.     3.  Daphnia  pulex. 


FIG.  126. — Metamorphosis  of  Crustacea,  (Carcinus  mcenas.}    a.  Larval  or  first  form. 
b.  Second  stage,     c.  Third  stage,    d.  Final  stage,  in  which  the  metamorphosis  is  complete. 

4.)  Decapods,  having  ten  legs,  as  the  Shrimp,  (Crangon^) 
Cray-fish,  Lobster,  (Astacus^)  and  Crab,  (Cancer^  Crabs 
differ  from  Lobsters  chiefly  in  being  formed  for  creeping 


THE  SCIENCE  OF  LIFE. 

at  the  bottom  of  the  sea  instead  of  for  swimming,  and 
in  the  abdomen,  or  tail,  being  a  mere  rudiment  which 
folds  into  a  groove  under  the  enormous  thorax.  The 
curious  metamorphosis  of  the  Crabs  is  illustrated  in 
Fig.  126.  At  first  the  embryo  is  a  comical-looking  ani- 
mal, with  a  sort  of  spiked  helmet  on  its  head.  It  has 
two  large  eyes  and  a  well-developed  abdomen.  It  is 
called  a  "Zoea,"  and  was  formerly  described  as  a  distinct 
genus.  After  a  succession  of  molts  it  becomes  a  per- 
feet  Crab. 

4.  ARACHNIDA  (arachne,  a  spider)  is  a  class  much  re- 
sembling the  Crustaceans,  having  the  body  divided  into 
a  cephalo-thorax  and  abdomen.  The  head  carries  two, 
six,  or  eight  eyes,  which  are  not  compound  bundles  of 
crystal  rods  covered  by  a  common  cornea,  as  in  Crusta- 
ceans, but  separate  transparent  cones  surrounded  with 
pigment.  Antennae  are  only  two,  if  present,  and  are  not 
used  as  "  feelers,"  but  serve  prehension  of  food.  Man- 
dibles are  always  present,  and  in  Scorpions  the  maxillary 
palps  form  pincers,  or  claws,  like  those  of  a  Ciab.  Such 
claws  are  called  chela,  (chele,  a  claw.)  Arachnids  are  all 
air-breathers,  having  spiracles  which  open  into  air-sacs, 
or  tracheae.  The  young  of  the  higher  forms  undergo  no 
metamorphosis  after  leaving  the  egg.  The  class  is  di- 
vided into  three  orders  :  Mites,  Scorpions,  and  Spiders. 

I.)  Mites  are  the  simplest  forms  of  the  class.  They 
have  no  marked  articulations,  the  head,  body,  and 
thorax  being  in  one  piece.  They  have  no  brain,  but  a 
single  ganglion  in  the  abdomen.  They  breathe  by  tra- 
cheae. The  mouth  is  formed  for  suction.  Most  are 
parasitic  on  animals  or  plants.  Mites  (Acarus)  include 


ARTICULATA.  225 

the  Cheese -mite,  the  Itch -insect,  and  many  similar 
forms.  The  Ticks  (Ixodes)  have  a  piercing  beak  and  a 
leathery  skin. 

2.)  Pedipalpi,  or  Scorpions,  have  maxillary  palpi  ending 
in  forceps,  and  a  prolonged  jointed  abdomen.  (Fig.  127.) 
Breathing  takes 
place  by  pulmo- 
nary sacs,  similar 
to  spiders.  The 
nervous  and  cir- 
culatory systems 
are  highly  organ- 

,          rr ,          ,  FIG.  127.— Scorpion. 

ized.      The   last 

joint  of  the  abdomen  bears  in  scorpions  a  sharp  spine  at 
its  end,  perforated  by  the  duct  of  a  poison-gland, 
whereby  it  inflicts  painful  wounds.  The  Chelifer,  or 
Book-scorpion,  sometimes  found  in  old  books,  has  no 
sting.  The  Phalangers,  or  Harvest-spiders,  with  long 
hooked  palpi  and  long  ungainly  legs,  belong  to  this 
order. 

3.)  Araneida,  or  Spiders,  have  the  cephalo-thorax 
joined  to  the  sac-like  abdomen  by  a  narrow  constriction, 
and  are  provided  at  the  posterior  end  with  two  or  three 
pairs  of  appendages  called  "spinnerets."  The  use  of  the 
spinnerets  is  to  reel  out  the  silk  for  their  web  from  the 
silk-glands.  The  tip  of  each  is  perforated  by  many  pores, 
through  which  the  silk  escapes,  so  that  each  thread  of 
the  web  may  consist  of  several  hundred  strands.  The 
silk  is  fluid  at  first,  but  rapidly  hardens.  The  hind  feet 
have  comb-like  claws  for  pressing  the  silk  together. 
Sometimes  one  pair  of  the  hinder  appendages  consists 


226  THE  SCIENCE  OF  LIFE. 

of  palpiform  organs.  The  mandibles  are  vertical,  and 
end  in  a  powerful  hook.  The  maxillae,  or  palpi,  which  in 
Scorpions  are  powerful  claws,  in  Spiders  resemble  thor 
racic  feet.  The  brain  is  of  large  size,  and  the  nervous 
system  greatly  concentrated. 

The  instincts  of  Spiders  are  very  remarkable.  They 
are  the  most  wily  of  Articulates.  They  display  great 
skill  and  industry  in  weaving  their  webs,  and  some  spe- 
cies (called  Mason-spiders)  excavate  cavities  in  the 
ground,  which  they  line  with  a  silken  web,  and  close  the 
entrance  with  a  lid  which  moves  upon  a  hinge. 

5.  MYRIAPODA  (myrios,  numerous ;  pous,  foot)  is  a 
small  class,  including  the  Centipedes  and  the  Millipedes. 
The  body  is  divided  into  segments,  twenty  or  more, 
to  each  of  which  legs  are  appended.  They  resemble 
Worms  in  their  form,  and  in  the  simplicity  of  their  nerv- 
ous and  circulatory  systems;  but  the  skin  is  hardened 
by  chitine  and  the  legs  are  articulate.  They  breathe 
by  trachea,  or  tubes,  have  two  antennae,  and  a  variable 
number  of  eyes. 

I.)  Chilognatha,  (cheilos,  lip;  gnathos,  jaw.)  This  or- 
der contains  the  Thousand -legged  Worm,  (Julus.') 
The  body  is  round,  legs  very  numerous,  sometimes  a 
hundred  pairs,  each  segment  having  two  pairs.  Mouth 
without  palpi.  Lower  lip  composed  of  confluent  max- 
illae. They  are  of  slow  locomotion,  harmless,  and  vege- 
tarian. 

2.)  Chilopoda,  (cheilos,  lip  ;  pous,  foot,)  are  characterized 
by  a  flat  body,  with  fifteen  to  twenty  pairs  of  legs.  The 
mouth  possesses  a  hollow  duct  for  the  passage  of  fluid 
from  a  poison-gland.  The  terminal  section  of  the  body 


ARTICULATA. 


227 


carries  a  pair  of  spines.  Sometimes  the  tail  is  curved 
into  a  formidable  poisonous  hook,  as  in  the  Scorpion. 
In  temperate  climates  the  Chilopoda  are  harmless,  but 
often  dangerous  in  hot  countries.  Such  is  the  Centipede, 
(Scolopendra^} 

6.  INSECTA.  This  class  contains  more  species  than 
all  the  rest  of  the  Animal  Kingdom,  150,000  having 
been  already  described.  Its  typical  character  is  well 


FIG.  128.— Diagram  of  Insect,  (Blatta  orientalist  a.  Head  with  compound  eyes  and 
antennae,  b.  Prothorax  with  first  pair  of  legs.  c.  Mesothorax  with  second  pair  of  legs 
and  first  pair  of  wings,  d.  Metathorax  with  third  pair  of  legs  and  second  pair  of  wings. 
e.  Abdomen  without  limbs,  but  carrying  terminal  appendages,  which  are  subservient  in 
reproduction. 

marked,  yet  it  contains  a  large  number  of  instances  of 
special  structure,  arranged  for  evident  purpose.  Chap. 
Ill,  Sec.  9,  and  Chap.  V,  Sec.  6. 

The  body  is  divided  into  three  principal  segments — 


228  THE  SCIENCE  OF  LIFE. 

a  head,  a  threefold  thorax,  and  a  ringed  abdomen. 
(Fig.  128.) 

The  head  contains  the  organs  of  sense,  and  sup- 
ports two  antennae,  which  are  supposed  to  be  organs  of 
touch  and  of  hearing,  as  well  as  of  communication  be- 
tween one  insect  and  another.  There  are  many  forms 
of  antennse,  but  all  are  tubular  and  jointed.  The  eyes 
are  usually  compound,  although  there  are  also  some- 
times a  cluster  of  simple  eyes,  or  ocelli.  The  compound 

eyes  have  a  trans- 
parent surface,  or 
cornea,  divided 
into  many  facets, 
each  of  the  nerve- 
rods  having  its 
own  pigment  mass 
A  nG',,I29'THrd  and  fyesf  *  «e  Bner  "'  "'  Af"na;-  and itsown cornea. 

b.  Ocelli.     A.  Facets  enlarged.      B.   1  he  same  with  hairs 

growing  between  them.  (Fig.      129.)          The 

common  house-fly  has  two  thousand  such  facets  in  each 
eye,  and  in  the  dragon-fly  there  are  twenty-eight  thou- 
sand. 

The  thorax  consists  of  three  pieces,  the  prothorax, 
mesothorax,  and  metathorax,  each  having  a  pair  of  legs ; 
the  wings,  when  present,  arise  from  the  last  two  seg- 
ments. 

The  abdomen  contains  the  viscera  and  the  organs  of 
reproduction.  Legs  are  never  attached  to  it. 

The  "  brain,"  as  it  is  called,  is  a  mass  of  ganglia  lying 
across  the  upper  side  of  the  throat  behind  the  mouth, 
and  the  principal  nerve  cord,  with  a  ganglion  for  each 
segment,  runs  along  the  ventral  side  of  the  body. 


ARTICULATA. 


229 


FIG.  130. — Circulation  in  Insects.     The  arrows  indicate  the  course  of  the  blood. 

The  digestive  apparatus  consists  of  pharynx,  gullet, 
(sometimes  a  crop,)  gizzard,  stomach,  and  intestine. 
The  liver  is  represented  by  tubes  opening  into  the 
intestine.  Many  insects  have  glandular  tubes,  called 


a  b  c  d  e  h  f  g 

FlG.  131.— Digestive  Apparatus  of  Beetle,    a.  Pharynx,    b.  (Esophagus,   c.  Crop.    d.  Giz- 
zard,   e.  Chylific  stomach,  f.  Small  intestine,  g.  Rectum,   k.  Biliary  vessels. 

from  their    first    describer,   Malpighian,  which   open   at 
the  end  of  the  intestine.     (Fig.  131.)     Some  have  also 

salivary  glandular  tubes  and  silk  organs,     Insects  have 
20 


230 


THE  SCIENCE  OF  LIFE. 


no  absorbent  vessels,  the  chyme  transuding  through  the 
walls  of  the  canal.  The  blood,  usually  colorless,  is  pro- 
pelled by  a  pulsating  tube  divided  into  valvular  sacs, 
which  allow  the  current  to  flow  only  toward  the  head. 

(Fig.  130.) 


Head. 


First  Pair  of  Legs 


First  Segment  of 
Thorax 


Origin  of  Wing 
Second  Pair  of  Legs 
Third  Pair  of  Legs 


Tracheae 
Stigmata 


Air-sacs 


FIG.  132. — Respiratory  Apparatus  of  Inseet,  (Neja.) 

From  this  tube  it  escapes  into  the  cavities  of  the  body. 
Respiration  is  provided  for  by  a  tracheal  system  ;  the 
air  circulating  in  vessels  instead  of  the  blood,  as  in  other 
classes.  A  row  of  apertures  (spiracles)  on  each  side 
of  the  body,  often  provided  with  a  net-work  of  fibers 


ARTICULATA.  231 

to  keep  out  foreign  substances,  communicate  with 
branching  tubes,  whose  membraneous  wall  is  strength- 
ened and  kept  open  by  a  coiled  spinal  filament.  (Fig. 
132.)  What  are  called  the  "  nerves"  of  an  Insect's  wing 
are  double  tubes,  the  inner  one  being  a  tracheal  branch 
supplying  air,  and  the  outer  one,  sheathing  it,  is  a  blood- 
vessel. 

The  mouth  of  an  Insect  is  a  very  complicate  appara- 
tus. Some  are  Masticatory,  or  fit- 
ted for  biting,  as  in  Beetles.  (Fig. 
133.)  Others  are  Suctorial,  or  for 
sucking,  as  in  Butterflies.  These 
last  form  a  long  double  tube,  or 
spiral  trunk,  (proboscis,)  serving  to 
pump  up  the  juices  of  flowers. 
The  masticating  mouths  consist  of 
two  pairs  of  horny  jaws,  (mandibles  FIG.  i33.— Masticatory  mouth 

,  •//      \         1   •    1  i      1  of  Insect.   <z.  Labrum,  or  upper 

and  maxilla,)  which  work  horizon-  lip.    3.  Labium,  or  lower  HP, 


tally  between  an  upper  (labrunf)  lip 

and    an    under   (labium)   lip.      The  bles< 

maxillae  and   under  lip   carry  sensitive   jointed   feelers, 

(palpi.)      The    front    edge   of  the    labium    is   generally 

known  as  the  tongue,  (ligula.) 

In  the  Bee  tribe,  instead  of  maxillae,  we  find  a  sheath 
inclosing  a  long,  slender,  hairy  tongue.  Entomologists 
have  retained  the  same  names  to  the  different  parts, 
under  the  influence  of  the  theory  of  transmutation. 
(Fig.  134.) 

The  proboscis  of  the  Fly  is  an  enlarged  lower  lip, 
(Fig.  135;)  that  of  the  Bugs  is  formed  by  four  bristles, 
fitted  both  for  piercing  and  sucking. 


232 


THE  SCIENCE  OF  LIFE. 


Mandible.    


Maxillary  Palp. 


Maxilla. 


Labial  Palp. 


Antenna 


Lateral  Lobes  of 

the  Tongue.      remaining 


Tongue. 


FIG.  134.— Head  of  a  Bee. 


Most  Insects  undergo  metamorphosis,  and  exhibit 
four  states  of  existence :  egg,  larva,  pupa,  and  imago. 

The  larva  has  lit- 
tle resemblance  to 
its  parent,  eating 
and  growing  rapid- 
ly. It  wraps  itself 
in  a  cocoon  and  en- 
ters the  pupa  state, 
'  ig  appar- 
ently dead  till  new 
organs  are  devel- 
oped, when  it  emer- 
ges a  perfect  winged 
Insect,  or  imago. 
Insects  have  six  legs,  each  having  five  parts ;  the 
coxa  or  hip,  the  trocliantcr,  the  tibia  or  shank,  and  the 

tarsus.  The  last 
is  subdivided  into 
joints,  generally 
five,  and  a  pair  of 
claws.  Such  as  can 
walk  on  glass,  or 
upside  down,  as  the  Fly,  have  two  or  three  disks  (pul- 
villi)  between  the  claws.  It  used  to  be  supposed  that 
these  disks  acted  as  suckers,  but  it  is  now  believed  that 
each  hair  is  a  minute  tube  containing  a  viscid  fluid  by 
which  the  Fly  adheres. 

The  male  of  the  Great  Water-beetle  (Dytiscus  mar- 
ginalis]  has  a  peculiar  apparatus  of  suckers,  large  and 
small,  on  his  front  legs,  which  may  be  useful,  but,  judg- 


FIG.  i35.-Proboscis  of  a  Dipterous  Insect,  (Tabanus.) 


ARTICULATA. 


233 


ing  from  their  beautiful  fringes  as  seen  under  the  mi- 
croscope, appear  rather  ornamental.     (Fig.  137.) 


FIG.  136. — A.  Larva  of  Mosquito.     E.  Escape  of  Mosquito  from  its  i-u^-caae 

Order  I.   Neuroptera ;  (neuron,  nerve;  pteron,  wing,) 
includes  Dragon   flies,  (Libellulidce,  (Fig.    138;)    Caddis 


FIG.   137.— A.  Foot  of  Dytiscus^  showing  its  apparatus  of  suckers,     a.  b.  Large  suckers. 
c.  Ordinary  suckers.     B.  One  of  the  ordinary  suckers  more  highly  magnified. 

flies,  (Plioganeidcz,}  May  flies,  (Ephemeridce,}  the  Ant- 
lion,  (Mygonalis,)  and  the  Termite  Ants.  The  mouth 
is  masticatory ;  wings  four,  equal  in  size,  membraneous 

and  lace-like. 
30* 


234 


THE  SCIENCE  OF  LIFE. 


Order  2.  Orthoptera ;  (prthos,  straight;  pteron,  wing,) 
embraces  the  Crickets,  (Achetina^)  Grasshoppers,  (Gryl- 
lina,)  (Fig.  138,)  Locusts,  (Locustina,)  and  Cockroaches, 


FIG.  138.— i.  Dragon-fly,  (Libellulina  dejressa.)  2.  Grasshopper,  (Gryllus.)  3.  Bee, 
(Afzs  mellijica.)  4.  Fly,  (Musca  domestica.)  5.  Butterfly,  (Pontia  brassica.)  6.  Musk- 
beetle,  {Cerambyx  moschatus.) 


(Blattina.} .  Mouth  masticatory.  Wings  four,  or  want- 
ing ;  anterior  pair  small,  thickened,  and  overlapping 
along  the  back ;  the  hinder  pair  broad,  net-veined,  and 
folding  like  a  fan.  Legs  various,  being  powerful  jump- 
ing organs  in  grasshoppers,  raptorial  (raptor,  a  plun- 
derer) in  Mantis ;  cursorial  (ciirro,  to  run)  in  Locusts. 
Each  family  produces  sounds  which  are  characteristic, 
and  which  are  supposed  to  be  produced  by  the  rapid 
friction  of  the  long  hind  legs  against  the  wing.  The 
sound  of  the  Grasshopper  is  said  to  be  the  highest 
known  musical  note. 


ARTICULATA.  235 

Order  3.  Hemiptera,  (hemi,  half;  pteron,  wing,)  have  a 
suctorial  mouth,  produced  into  a  long,  hard  beak.  The 
four  wings  are  irregular  and  sparsely  veined,  or  wanting. 
The  body  is  flat  above,  and  the  legs  slender.  In  some 
the  four  wings  are  opaque  at  the  base,  and  transparent 
at  the  apex,  whence  the  name  of  the  order.  Some  feed 
on  the  juices  of  animals,  and  some  on  plants.  Plant-lice, 
(Aphides?)  the  wingless  Bed-bug,  (Cimex^)  and  Louse, 
(Pediculus?)  the  Squash-bug,  (Coreus,)  Water-boatman, 
(Notonecta^)  Seventeen-year  Locust,  (Cicada^)  and  the 
Cochineal,  (Coccus?)  are  examples. 

Order  4.  Coleoptera.  (Koleos,  a  sheath  ;  pteron,  wing.) 
This  is  the  largest  of  the  orders,  containing  about  ninety 
thousand  species.  The  thickened,  horny  fore-wings,  or 
elytra,  (elytron,  a  sheath,)  are  not  used  for  flight,  but  to 
cover  the  hind  pair.  When  at  rest  the  elytra  are  united 
by  a  straight  edge  along  their  length,  and  the  hind  wings 
are  folded  transversely.  The  mouth  is  armed  with  for- 
midable mandibles;  the  integument  is  generally  hard, 
and  the  legs  are  strong.  The  larvae  are  worm-like,  and 
the  pupa  is  motionless.  The  highest  tribes  are  carniv- 
orous. Among  them  we  find  the  Tiger-beetles,  (Cicin- 
delal)  the  common  Ground-beetles,  (Carabus^)  whose  hind 
wings  are  often  absent,  the  Diving-beetles,  (Dytiscus^) 
with  boat-like  body  and  oar-like  hind  legs,  the  Carrion- 
beetles,  (Silpha^)  with  black,  flat  bodies  and  club-shaped 
antennae,  the  Goliath-beetles,  (Scarabceus,)  the  Snap- 
ping-bugs,  (Elata?)  the  Lightning-bugs,  (Pyrophorus?) 
the  spotted  Lady-birds,  (Coccinella^)  the  Long-horned 
beetles,  (Cerambycidce?)  and  the  destructive  Weevils, 
(Curculionidce^)  with  pointed  snouts.  (Fig.  138.) 


236  THE  SCIENCE  OF  LIFE. 

Order  5.  Diptera,  or  two- winged  Flies;  have  the  hinder 
pair  of  wings  replaced  by  "  poisers/'  or  "halteres"  A 
few  species  are  wingless.  The  eyes  are  large,  with  many 
facets ;  the  tongue  terminates  in  a  fleshy  knob,  and  the 
rest  of  the  mouth  is  suctorial,  and  furnished  with  fine 
lancets ;  the  thorax  is  globular,  and  the  legs  slender. 
The  larvae  are  footless  grubs.  Among  them  are  House- 
flies,  (Musccz?)  (Fig.  138,)  Gnats,  (Culicidce^)  Crane-flies, 
(  Tipulida, )  Forest-flies,  ( Hippoboscce, )  and  Gad-flies, 
(Gabrinufo!)  The  wingless  Flea  (Pulex)  is  also  placed 
in  this  order. 

Order  6.  Lepidoptera,  (lepis,  scale ;  ptcron,  wing,)  in- 
cludes Butterflies  and  Moths.  They  have  four  large 
wings,  thickly  covered  on  both  sides  with  minute  over- 
lapping scales,  of  different  colors,  and  often  arranged  in 
patterns  of  exquisite  beauty.  These  scales  are  epider- 
mic appendages  of  a  similar  nature  to  hairs,  and  every 
family  has  a  special  form  of  scale.  The  head  is  small, 
the  body  is  cylindrical,  and  the  legs  are  little  fitted  for 
locomotion.  The  mouth  is  a  proboscis,  or  coiled  tube, 
sometimes  an  inch  long.  The  caterpillar,  or  larva,  has  a 
worm-like  form,  and  from  one  to  five  pairs  of  abdominal 
legs,  in  addition  to  the  six  on  the  thorax.  The  mouth 
is  formed  for  mastication. 

There  are  three  groups :  the  gay  Butterflies,  (Fig. 
138,)  having  knobbed  or  hooked  antennae,  flying  in  the 
sunshine  only,  and  keeping  their  wings  vertical  when  at 
rest ;  the  dull-colored  Sphynges,  or  evening  Moths,  with 
antennae  thickened  at  the  middle,  and  flying  at  twilight ; 
and  the  nocturnal  Moths,  whose  antennae  are  thread- 
like and  often  feathery,  and  which  prefer  the  night. 


ARTICULATA.  237 

The  pupa  of  Butterflies  is  unprotected,  and  is  generally 
suspended  by  a  silken  thread.  The  pupa-case  is  gen- 
erally ornamented  with  golden  spots,  hence  the  com- 
mon name,  chrysalis.  The  pupa  of  Moths  is  inclosed 
in  cocoons. 

Order  7.  Hymenoptera,  (hymen,  membrane;  pteron^ 
wing,)  includes  Bees,  (Fig.  138,)  Wasps,  Ichneumons, 
Saw-flies,  and  Ants.  The  mouth  is  fitted  for  both  biting 
and  suction ;  the  legs  are  for  locomotion  as  well  as  sup- 
port ;  and  the  four  membraneous  wings  are  equally  trans- 
parent, and  interlock  by  small  hooks  during  flight.  The 
females  are  usually  provided  with  a  sting,  or  borer.  The 
larvae  are  footless,  helpless  grubs,  generally  nurtured  in 
cells,  or  nests. 

The  colony  of  Bees  is  formed  of  the  perfect  female, 
called  the  "  Queen-bee,"  many  perfect  males,  or  drones, 
and  a  swarm  of  sexless  bees,  the  neuters,  or  workers. 
The  drones  and  the  neuters  are  produced  by  partheno- 
genesis. (Chap.  Ill,  Sec.  16.) 

The  "vespiary"  of  the  Wasps,  like  the  hive  of  the 
Honey-bee,  contains  males,  females,  and  neuters ;  but 
the  perfect  males  work  equally  with  the  neuters. 

Ants  (Formicidce)  also  form  colonies,  and  the  observa- 
tions made  upon  many  species  show  a  wonderful  amount 
of  intelligence  in  these  creatures.  In  many  ant-colonies 
the  neuters  consist  of  two  classes — "  the  workers,"  who 
do  all  the  building  and  storing  of  the  little  town,  and 
"  the  soldiers,"  who  defend  the  works.  Their  treatment 
of  Plant-lice,  or  Aphides — keeping  them,  and  milking 
them  as  men  do  cows — their  slave-capturing  expeditions, 
and  the  recently-discovered  agricultural  ant-colonies, 


238  THE  SCIENCE  OF  LIFE. 

furnish  abundant  food  for  the  propensity  to  the  mar- 
velous in  human  nature,  and  prove  to  the  philosophic 
observer  of  creation  how  closely  related  are  all  living 
things  to  properties  of  thought,  affection,  and  will, 
which  are  generally  regarded  as  spiritual  ratLer  than 
material. 


VERTEBRATA.  239 


CHAPTER   XV. 

VERTEBRATA. 

Thus  the  seer, 

With  vision  clear, 

Sees  forms  appear  and  disappear, 

In  the  perpetual  round  of  strange 

Mysterious  change 

From  birth  to  death,  from  death  to  birth, 

From  earth  to  heaven,  from  heaven  to  earth  ; 

Till  glimpses  more  sublime 

Of  things  unseen  before, 

Unto  his  wondering  eyes  reveal 

The  Universe,  as  an  immeasurable  wheel 

Turning  for  evermore 

In  the  rapid  and  rushing  river  of  Time. 

—  LONGFELLO  \V. 

i.  THE  type,  or  sub-kingdom,  Vertebrata,  (vertebra,  a 
joint  of  the  back,  from  vertere,  to  turn,)  is  characterized 
by  the  separation  of  the  greater  part  of  the  nervous  sys- 
tem from  the  general  cavity  of  the  body.  A  transverse 
section  of  the  body  exhibits  two  cavities,  or  tubes ;  the 
dorsal,  or  neural,  tube,  containing  the  cerebro-spinal 
nervous  system,  and  the  ventral,  or  haemal  tube,  inclos- 
ing the  alimentary  canal,  heart,  lungs,  and  a  double  chain 
of  ganglia  belonging  to  the  sympathetic  system  of  nerves. 
The  ventral  cavity,  with  its  contents,  corresponds  to  the 
whole  body  of  an  Invertebrate  animal,  while  the  dorsal 
tube  is  distinctly  typical.* 

Vertebrates  have  an  internal,  jointed  skeleton,  capable 

*  See  Frontispiece. 


240 


THE  SCIENCE  OF  LIFE. 


of  growth  and  repair.  (Chap.  IV,  Sec.  13,  d.)  During 
embryonic  life  it  is  represented  by  the  notochord,  a  fibro- 
cellular  rod,  tapering  to  either  end,  but  this  is  replaced 
by  a  more  highly  developed  column  of  cartilage  or  bone, 
except  in  the  doubtful  Amphioxus.  The  column  and 
cranium  are  never  absent,  although  other  parts  may  be 
wanting,  as  the  ribs  in  Frogs,  limbs  in  Snakes,  etc.  The 
limbs  never  exceed  four,  and  when  present,  are  always 
articulated  to  the  internal  skeleton,  on  the  ventral  side 
of  the  body,  while  the  limbs  of  Invertebrates  are  devel- 
oped from  an  external  skeleton,  on  the  neural  side.  The 


FIG.  139. — Muscular  Fibers.     Magnified  200  diameters. 

muscles  moving  the  limbs  are  attached  to  the  endoskel- 
eton  and  not  to  the  exoskeleton,  as  in  Invertebrates. 
Muscular  tissue  is  found  in  all  animals,  from  Radiates  to 
Man.  The  most  complete  development  of  muscles  is  in 
the  Pentacrinus.  (Chap.  XII,  Sec.  5.)  Voluntary  mus- 
cular tissue  always  has  a  transversely  striated  appearance 
under  the  microscope,  (Fig.  139,)  while  those  fibers  not 
under  the  control  of  the  will  are  smooth. 


41 


VERTEBRATA.  2 

. 

The  circulation  of  the  blood  is  complete  in  Vertebrates, 
the  arteries  being  joined  to  the  veins  by  capillaries,  so 
that  the  blood  never  escapes  into  the  visceral  cavity,  as 
in  the  Invertebrates.  All  have  a  portal  vein,  carrying 
blood  through  the  liver,  and  all  have  lacteals  and  lym- 
phatics. The  blood  is  red,  and  contains  both  red  and 
white  corpuscles.  The  teeth  are  developed  from  the 
dermis,  never  from  the  cuticle,  as  in  Mollusks  and  Artic- 
ulates ;  the  jaws  move  vertically,  and  are  never  modified 
limbs.  The  liver  and  kidneys  are  always  present.  The 
respiratory  organs  are  either  gills  or  lungs,  or  both. 
Vertebrates  are  the  only  animals  which  breathe  through 
the  mouth. 

The  arrangement  of  the  circulatory  system  varies  i:i 
the   different  classes,  in  accordance  with 
the   structure  of  the    respiratory   organs. 
In  Fishes  (Fig.  140)  the  heart  is  double 
as  in  the  Oyster,  but  instead  of  drivh\ 
arterial  blood  over  the  body,  it  receive.; 
the  returning,  or  venous  blood,  and  sends 
it  to  the  gills.     From   the   capillaries  of 
the  gills  the  blood  is  passed  into  a  large 
artery,  or  aorta,  along  the  back,  which 
distributes  it  by  a  complex  net-work  of 
capillaries  among  the  tissues.    These  cap- 
illaries unite  with  the  ends  of  the  veins 
which  pass  the  blood  into  the  auricle  of 

the  heart,  after  purification  in  the  liver   ";Auri<;le-  ^-Ventri- 
cle, c.  Pulmonary  Ar- 

and  kidneys.  tefy-    e-  Pulmonary 

Veins,  bringing  blood 

In  Amphibia  and   Reptiles  (Fig.   141)   from  the  giiis,  </,  and 

uniting  in  the  Aorta, 

the  heart  has  three  cavities;  two  auricles   /.  s. 
£1 


242 


THE  SCIENCE  OF  LIFE. 


and  one  ventricle.  The  venous  blood  from  the  body  is 
received  into  the  right  auricle  and  the  purified  blood 

from  the  lungs  into  the 
left.  Both  communi- 
cate with  the  ventricle, 
which  pumps  the  mixed 
blood  part  to  the  lungs 
and  part  around  the 
system. 

The  highest  form  of 
circulation  is  seen  in 
the  warm-blooded  Ver- 
tebrates, Birds,  and 
Mammals.  The  heart 

FK;.  141. — A.  Plan   of  Circulation   in  Amphibia 

and  Reptiles.     B.  Plan  of  Circulation  in  Birds  and  has       foUT      CaVltlCS 3. 

Mammals,    a.  Right  Auricle  receiving  venous  blood 

from  tbe  system,     b.  Left  Auricle  receiving  arterial  Tight     aild  left     auricle, 

blood  from  the  lungs,    c.  c' .  Ventricles,    d.  e.f.  Sys-             ,                .  1  j      i     r 

temic  Artery,  Vein,  and  Capillaries,    g.  h.  k.  Pul-  and     a     ngftt      and      left 

monary  Artery,  Vein,  and  Capillaries.  ventricle.  The      right 

auricle  receives  the  blood  from  the  veins,  transmits  it  to 
the  right  ventricle,  which  sends  it  to  the  lungs.  The 
left  auricle  receives  it  from  the  lungs,  and  sends  it  to  the 
left  ventricle,  which  propels  it  over  the  body.  The  two 
auricles  contract  together,  and  so  also  do  the  ventricles, 
making  certain  faint  sounds,  which  may  be  imitated  by 
the  words  lubb  tup.  (Fig.  141.) 

The  greatest  differences  between  Vertebrates  and  other 
animals  are  found  in  the  Nervous  system,  which,  as  we 
have  seen,  has  a  distinct  tube  or  cavity  in  this  type,  al- 
together unlike  the  plan  of  structure  elsewhere. 

In  living  things,  like  the  Protozoa,  or  Protophytes, 
which  are  composed  of  a  simple  mass  of  bioplasm,  all 


VERTEBRATA.  243 

the  functions  necessary  for  animal  or  vegetable  life  belong 
equally  to  every  atom  of  the  mass.  In  Chap.  V,  Sec.  7, 
it  was  shown  that  the  simplest  plants  and  animals  differ 
from  the  highest,  or  more  complex,  only  in  the  modi- 
fication of  some  parts  of  the  structure  to  serve  special 
functions.  Thus  locomotion  is  served  by  the  change  of 
bioplasm  into  muscle,  or  bone,  external  protection  by 
transformed  epidermal  bioplasm,  as  described  in  Chap. 
IV.  To  regulate  and  harmonize  the  complex  organs  of 
digestion,  respiration,  circulation,  and  secretion,  and  to 
conduct  sensation  and  motor  force,  seems  to  have  been 
the  object  of  the  change  of  bioplasm  into  nervous  matter. 

Nerve  matter  exists  in  the  form  of  cells  and  of  fibers. 
The  cells  are  soft  and  grayish,  and  are  generally  found 
accumulated  in  masses  or  ganglia,  sometimes  called 
nerve-centers.  The  fibers  are  of  two  kinds,  one  soft  and 
nucleated,  the  ganglionic  or  sympathetic  fibers,  and  or- 
dinary nerve-fibers. 

These  latter  are  for  a  great  part  of  their  length  in- 
closed in  a  transparent  sheath,  which  coagulates  after 
death  into  a  white  substance — the  white  substance  of 
Schwann.  A  number  of  these  fibers,  thus  ensheathed, 
are  bound  in  bundles,  which  are  called  nerves.  Some  of 
these  fibers  proceed  or  conduct  impressions  from  the 
surface,  or  from  the  different  organs  where  they  are 
found,  toward  the  gray  centers  only,  and  are  called  af- 
ferent or  sensory  nerves.  Others  conduct  an  influence 
from  the  centers  to  contract  or  move  the  muscles,  and 
are  called  efferent,  or  motor  nerves.  Thus,  on  receiving 
any  impression,  as  the  prick  of  a  pin,  an  afferent  nerve 
conducts  the  impression  to  the  center,  from  which  an 


244  THE  SCIENCE  OF  LIFE. 

efferent  nerve  conducts  power  for  the  muscles  to  contract. 
If  the  afferent  nerve  of  a  part  is  cut  across  or  injured, 
sensation  is  lost,  but  motion  remains ;  but  if  the  efferent 
nerve  is  cut,  the  power  of  motion  is  lost  while  sensibility 
continues.  This  form  of  nerve-action  is  called  reflex. 
Many  actions  of  this  sort  are  wholly  involuntary,  as  the 
motions  of  the  limbs  in  paralytics  excited  by  tickling  the 
soles  of  the  feet. 

In  the  Star-fish  we  find  a  nervous  ring  around  the 
mouth,  made  of  five  ganglia,  with  radiating  nerves,  cor- 
responding with  the  type  of  structure.  The  Mollusks 
have  an  irregularly  scattered  nervous  system,  consisting 
of  two  or  more  ganglia  around  the  gullet  and  one  or  two 
more  in  the  posterior  region,  united  by  threads,  and 
sending  fibers  to  various  organs.  The  Articulates  have 
generally  a  double  nervous  cord  along  the  ventral  side, 
studded  with  ganglia  of  nearly  uniform  size,  except  the 
first,  which  is  largest.  In  the  higher  forms,  as  the  Bee, 
several  ganglia  are  fused  together  in  the  head  and  tho- 
rax, indicating  a  concentration  of  organs  for  sensation 
and  locomotion. 

The  nervous  system  of  the  Invertebrates  is  Jiomolog- 
ically  represented  by  the  ganglionic  or  sympathetic  sys- 
tem of  Vertebrates,  which  supplies  the  unstriped  or  in- 
voluntary muscles,  and  presides  over  organic  or  visceral 
functions,  such  as  digestion  and  circulation.  In  addition 
to  the  sympathetic  system,  Vertebrates  have  a  brain  and 
spinal  cord,  forming  the  cerebro-spinal  system,  (Fig.  142,) 
to  which  there  is  nothing  similar  in  other  animals,  and 
which  presides  over  what  are  called  the  functions  of  ani- 
mal or  sentient  life,  as  sensation  and  locomotion.  Yet 


VERTEBRATA. 


245 


as  many  Invertebrates  exhibit  sensibility  and  voluntary 
actions,  it  follows  that  analogically  the  nervous  system 
in  them  represents  both  the  sym- 
pathetic and  cerebro-spinal  systems 
of  Vertebrates. 

The  form  of  the  brain  differs  much 
among  Vertebrates.  In  some  the 
cerebral  hemispheres  are  small ;  in 
certain  Fishes  smaller  than  the  optic 
lobes  ;  in  the  higher  tribes  they  near- 
ly or  quite  overlap  both  olfactories 
and  cerebellum.  The  brain  may  be 
smooth,  as  in  most  cold-blooded  ani- 
mals, or  greatly  convoluted,  as  in 
Man. 

Vertebrates  are  subdivided  into  five 
classes:  Fishes,  Amphibians,  Reptiles, 
Birds,  and  Mammals.  The  first  three 
are  cold-blooded,  the  other  two  warm- 
blooded. Fishes  and  Amphibians 
agree  in  having  gills  during  all  or  a 
part  of  their  lives.  The  rest  never 

have   gills.  FlG>  M*-  — Human  Brain 

and  Spinal   Cord,   one  fifth 

2.    FISHES,  (PlSCeS.)      These  are  COn-     natural  size-    «•  Great  longi- 
tudinal fissure,     b.  Anterior 

sidered  the  lowest  of  Vertebrates,  yet   lobe.  c.  Middle  lobe.  d.  Me 

,1  dulla  oblongata.    e.  Cerehcl 

they  are  so  numerous  as  to  embrace   iura.  /.  First  spinal  „««=. 
nearly  one  half  of  all  Vertebrates,  tjgSSZ*^ 

and    SO    Varied    that    it     is     difficult    tO     salnerves-    '.Lumbar nerves 

k.  Sacral  plexus  of  nerves  for 

frame  a  definition  which  shall  include   the  limbs-  l-  Cauda  equina. 

,.  The     figures     indicate     the 

all.  twelve  pairs  of  cranial  nerves, 

FishesHve  in  the  water  and  breathe 


246 


TIIK  SCIENCE  OF  LIFE. 


by  means  of  gills.  They  are  generally  covered  with 
scales,  and  they  have  fins  instead  of  limbs.  They  have 
large  immovable  eyes,  but  no  external  ears.  Both  jaws 
are  movable.  The  teeth  are  numerous,  and  are  gener- 
ally recurved  spines,  as  in  the  Pike ;  flat  and  triangular, 
with  serrated  edges,  in  the  Shark ;  and  tessellated,  in  the 
Ray.  The  digestive  tract  is  relatively  shorter  than  in 
other  Vertebrates.  The  blood  is  red,  and  the  heart  has 
two  cavities,  an  auricle  and  a  ventricle,  both  on  the 
venous  side.  Ordinary  fishes  have  four  gills,  the  water 
escaping  by  one  external  aperture,  or  "gill-slit;"  but  in 
Sharks  there  is  a  separate  opening  for  each  gill. 

There  are  four  principal  varieties  of  fish-scales.  (Fig. 
143.)     i.  Cycloid  scales,  (cyclos,  a  circle,)  which  are  most 

common ;  thin, 
flexible,  and  sil- 
very, as  in  the  Sal- 
mon. 2.  Ctenoid, 
(kteiS)  a  comb,) 
with  a  comb-like 
fringe  of  toothed 
processes.  3.  Ga- 
noid,  {ganos, 

FIG.  143.— Varieties  of  Fish  Scales.  <*.  Ctenoid  scale,  b.  Cy-      brightness,)     gCH- 

cioid  scale,  c.  Ganoid  scale,  d.  Placoid  scale.  erally  larger  than 

the  preceding,  and  having  an  under  layer  of  bone  with 
a  superficial  layer  of  enamel.  Most  ganoid  fishes  are 
extinct.  4.  Placoid,  (plax,  a  flat  plate ;)  these  are  formed 
of  bony  granules,  or  tubercles,  or  plates,  the  plates  often 
being  furnished  with  spines. 

Most  fishes  have  a  series  of  small  scales  running  along 


VERTEBRATA.  247 

the  side  of  the  body,  called  the  lateral  line.  Each  scale 
is  perforated  by  a  tube  which  runs  along  the  whole  length 
of  the  body,  and  is  connected  with  cavities  in  the  head 
which  secrete  the  mucus  for  lubricating  the  scales,  and 
enabling  the  fish  to  move  with  little  resistance. 

Order  I.  PharyngobrancJis,  (pharynx,  the  pharynx,  and 
bragchia,  gills.)  This  contains  but  one  member,  the 
Lancelet,  (Amphioxus  lanceolatus^)  which  burrows  in  the 
mud  of  the  Mediterranean  Sea.  It  is  such  an  eccentric 
creature,  without  skeleton,  limbs,  brain,  heart,  lym- 
phatics, or  red  blood,  that  it  can  hardly  be  considered  a 
Vertebrate  at  all.  Yet,  because  it  has  a  persistent  noto- 
chord,  evolutionists  have  made  much  ado  over  it,  and  it 
figures  largely  in  their  imaginary  Phylogenies.  (Chap.  Ill, 
Sec.  8.) 

Order  2.  Marsipobranchs,  (inarsipos,  a  pouch.)  They 
have  a  cartilaginous  skeleton  and  sac-like  gills,  but  no 
scales,  limbs,  or  lower  jaw,  and  only  one  nasal  organ. 
They  comprise  the  eel-like  Lampreys  and  Hags.  (Fig. 
144.)  The  mouth  is  round  and  sucker-like ;  and  in  the 


FIG.  144.— Lamprey. 

Hags  (Myxince)  contains  a  single  large  recurved,  serrated 
fang  for  piercing  the  bodies  of  their  prey.    Respiration  is 


248 


THE  SCIENCE  OF  LIFE. 


carried  on  by  muscular  little  pouches  (marsiipia)  placed 
on  the  sides  of  the  neck. 

Order  3.  Teleosts,  (teleios,  perfect  ;  osteon,  a  bone,)  in- 
cludes all  the  true  osseous  fishes.  The  skull  is  compli- 
cated, the  upper  and  lower  jaws  complete,  and  the  gills 
are  comb-like,  or  tufted.  The  tail  is  Jiomoccrcctl,  having 
equal  lobes.  The  other  fins  vary  in  number  and  position. 


a 


FIG.  145. — Gray  Mullet :    a.  First  dorsal  fin.    b.  Second  dorsal,     c.  Pectoral,    d. Ventral. 
e.  Anal.    f.  Caudal. 

In  the  soft-finnecl  Fishes,  the  ventral  fins  (Fig.  145)  are 
absent,  as  in  the  Eels ;  or  attached  to  the  abdomen,  as 


FIG.  146.— The  Cod. 

in  Salmon,  Herring,  Pike,  and  Carp;  or  placed  under  the 
throat,  as  in  the  Cod,  (Fig.  146,)  Haddock,  and  Flounder. 


VERTEBKATA. 


249 


In  the  spring-firmed  Fishes,  the  ventrals  are  generally 
under  or  in  front  of  the  pectorals,  and  the  scales  are  cte- 
noid, as  in  the  Perch,  Mullet,  and  Mackerel. 

Order  4.    Ganoids  include  the  Sturgeons,  (Fig.  147,) 


FIG.  147.— The  Sturgeon,  {Acipenser  Sturio.) 

Bony-pike,  Polypterus,  and  many  extinct  forms.  The 
skeleton  is  rarely  completely  ossified ;  the  ventral  fins 
are  placed  far  back,  and  the  tail  is  heterocercal,  or  une- 
qually lobed,  from  the  vertebra  continuing  in  the  upper 
lobe. 

Order  5.  Elasmobranchs  (clasma,  a  thin  plate)  contain 
Sharks,  Rays,  and  Chimeras.  The  gills  are  formed  of 
thin  laminae,  arranged  like  the  leaves  of  a  book.  They 
have  a  cartilaginous  skeleton,  and  a  harsh  skin  called 
"  shagreen."  The  gill-openings  are  uncovered,  and  the 
mouth  is  generally  under  the  head,  (except  in  the  Chi- 
merae.)  The  ventral  fins  are  placed  far  back,  the  pecto- 
rals are  large,  and  in  the  Rays  enormously  developed 
and  the  tail  is  heterocercal. 


250  THE  SCIENCE  OF  LIFE. 

Order  6.    Dipnoi,  (dis,  twice  ;  pnce,  breath,)  comprises 
the  Mud-fishes  (Lepidosircn)  of  tropical  rivers.  (Fig.  148.) 


FIG.  148. — Lepidosren. 

They  have  eel-like  bodies  covered  with  cycloid  scales. 
Both  ventral  and  pectoral  fins  are  present,  but  are  small 
filiform  organs,  nowise  resembling  ordinary  fins.  They 
have  rudimentary  external  gills,  and  internal  ones  which 
communicate  with  the  exterior  by  a  single  slit.  They 
also  possess  true  lungs,  which  communicate  with  the 
gullet  by  a  tube  or  trachea.  The  heart  has  two  auricles 
and  one  ventricle.  They  are  quite  Amphibian  in  struct- 
ure, and  live  long  out  of  the  water. 

3.  CLASS  II,  AMPHIBIA,  (0w//«, .  both ;  bios,  life,)  re- 
ceives its  name  from  the  animals  it  contains  being  able 
to  live  both  on  land  and  water.  They  are  cold-blooded 
Vertebrates  which  breathe  by  gills  during  some  part  of 
their  life,  but  sooner  or  later  possess  lungs.  Some  retain 
their  gills  through  the  whole  of  their  life,  as  the  Proteus, 
Siren,  and  Axolotl ;  others  lose  their  gills  after  a  time, 
and  breathe  by  lungs  only,  as  Frogs,  Toads,  and  Newts. 
All  undergo  metamorphoses  after  leaving  the  egg,  pass- 
ing through  the  "  tadpole"  state,,  in  which  they  resemble 
Fishes  in  their  respiration,  circulation,  and  locomotion. 

Order  i.  Urodela,  (oura,  a  tail ;  delos,  visible,)  the  tailed 
Amphibia.  They  have  a  naked  skin,  and  two  to  four 


VERTEBRATA. 


251 


legs.  The  aquatic  Newts  and  land  Salamanders  drop 
their  gills,  and  always  have  four  limbs. 

Order  2.  Labyrinthodontia  (labyrintkos,  a  labyrinth, 
odous,  a  tooth)  are  now  all  extinct.  They  resembled  gi- 
gantic Salamanders,  except  in  their  complex  teeth  and 
exoskeleton  of  bony  plates. 

Order  3.  GymnopJiiona,  (gymnos,  naked  ;  ophis,  a  snake,) 
also  called  Cecilia.  They  have  neither  tail  nor  limbs,  a 
snake-like  form,  minute  scales  in  the  skin,  and  numerous 
ribs. 

Order  4.  Batrachia,  or  Anoura.  (Fig.  149.)  (Batrachos, 
frog ;  ana,  without ;  oura,  a  tail.)  These  are  tailless 


FIG.  149. — i.  Frog,  (Rana  temporaria.)     2.  Toad,  (Bufo  vulgaris?)     3.  Tadpoles. 

Amphibia,  and  comprise  Frogs  and  Toads.  They  have 
a  naked,  moist  skin,  ten  vertebrae,  and  no  ribs.  They 
have  four  limbs,  the  hinder  longer  than  the  fore-legs. 
They  have  four  ringers  and  five  toes.  The  tongue  is 
long,  fixed  at  the  anterior,  and  doubled  up.  It  can  be 
thrown  out  rapidly  as  an  organ  of  prehension.  The  eggs 
are  laid  in  the  water,  enveloped  in  a  glairy  mass,  and  the 


252  THE  SCIENCE  OF  LIFE. 

tadpoles  are  like  the  Urodelans  till  the  gill  and  tail  arc 
absorbed.  Frogs  (Rand)  have  teeth  in  the  upper  jaw, 
and  webbed  feet.  Toads  (Bufd)  have  neither  teeth  nor 
webbed  feet. 

4.  Class  III.  REPTILIA,  or  Reptiles.  These  are  air- 
breathing,  cold-blooded  Vertebrates,  differing  from 
Fishes  and  Amphibians  by  never  having  gills,  and  from 
Birds  by  being  covered  with  horny  scales,  or  bony  plates. 
The  skeleton  is  ossified,  and  never  cartilaginous.  Most 
are  carnivorous,  and  teeth  are  present,  except  in  Turtles, 
where  a  horny  sheath  covers  the  jaws.  The  lungs  are 
imperfectly  cellular,  and  the  heart  is  three-chambered, 
containing  two  auricles  and  one  ventricle,  which  is  some- 
times divided  by  a  partition.  In  all  cases  a  mixture  of 
arterial  and  venous  blood  is  circulated.  The  limbs,  when 
present,  have  three  or  more  fingers  as  well  as  toes. 

There  are  four  orders  of  living  and  five  of  extinct 
Reptiles.  The  living  orders  are  Snakes,  Lizards,  Tur- 
tles, and  Crocodiles. 

i.)  Opliidia,  or  Snakes.  (Fig.  150.)  These  have  no 
visible  limbs,  but  a  vast  number  of  vertebrae.  The  Py- 
thon has  two  hundred  and  ninety-one,  the  Rattlesnake 
one  hundred  and  ninety-four,  and  the  Boa  Constrictor 
three  hundred  and  five.  They  have  immovable  trans- 
parent eyelids.  The  tongue  is  bifid  (cleft)  and  extensile. 
The  mouth  is  very  dilatable,  from  the  number  of  joints 
in  the  lower  jaw  united  only  by  ligament.  The  skin  is 
shed  in  one  piece  by  reversing  it.  Snakes  move  well 
either  on  land  or  in  water. 

Poisonous  snakes,  as  Vipers  and  Rattlesnakes,  usually 
have  a  triangular  head  covered  with  small  scales,  a  con- 


VERTEBRATA. 


253 


striction,  or  neck,  behind  the  head,  two  or  more  fangs  and 
few  teeth,  small  eyes  with  vertical  pupil,  and  short,  thick 


FIG.  150.— i.  Rock   Snake,  (Python  molurus^     2.  Spectacled  Snake,  (Cobra  de  Cap- 
fllo.     3.   Boa  Constrictor. 

tail.  In  the  harmless  Snakes  the  head  blends  with  the 
neck,  and  is  covered  with  plates,  (Fig.  151,)  the  teeth 
are  numerous  in  both  jaws,  the  pupil  is  round,  and  the 
tail  tapering. 

2.)  Lacertilia,  comprising  Chameleons,  Blindworms, 
and  Lizards,  are  distinguished  from  the  other  orders  by 
possessing  clavicles,  and  having  teeth  not  lodged  in  sock- 
ets, as  in  the  Crocodiles.  They  are  often  like  Snakes 
with  four  limbs,  each  having  five  digits.  Some  have  no 

exoskeleton,  but  it  is  generally  present  in  the  shape  of 

22 


254 


THE  SCIENCE  OF  LIFE. 


scales,  or  horny  plates,  or  spines.  In  the  Iguanidce  it  is 
elevated  into  a  crest,  or  mane,  of  horny  scales,  covering 
also  the  throat-pouches.  The  Draco  volans,  or  Flying 
Lizard,  has  a  cutaneous  expansion  from  the  false  ribs 
which  enable  it  to  take  short  flights  through  the  air. 


FIG.  151. — A.  Head  of  Harmless  Snake.     1).   Heads  of  Poisonous  Snakes  of  different 
genera. 

The  tongue  is  bifid  in  many  of  this  order,  but  in  Cha- 
meleons it  is  a  long,  round,  muscular  organ,  clubbed  at 
the  end,  and  coated  with  a  viscid  secretion,  by  means  of 
which  it  catches  great  numbers  of  flies  by  shooting  it 
out  with  remarkable  speed. 

3.  Chelonia,  or  Tortoises  and  Turtles.  These  resemble 
Amphibians  in  some  respects,  but  their  structure  is  very 
peculiar.  The  exoskeleton  unites  with  the  endoskeleton, 
forming  the  carapace,  or  case,  which  includes  the  viscera 
and  muscular  system.  The  vertebrae  are  soldered  to- 
gether and  the  ribs  are  expanded,  making  the  walls  of 
the  carapace.  The  ventral  piece  is  called  the  plastrom, 
or  sternum.  (Fig.  152.) 


VERTEBRATA.  255 

The  Sea-turtles,  as  the  edible  Green  Turtle  and  the 
Hawk's-bill  Turtle,  which  furnishes  the  tortoise-shell  of 
commerce,  have  the  limbs  formed  for  paddles.  The 
fresh-water  forms,  as  the  Snapping  Turtle,  (Chelydra^) 


FIG   152.— Skeleton  of  Turtle. 

are  amphibious,  and  have  palmated  feet.  Land  Tor- 
toises (Testudo)  have  short,  clumsy  limbs,  fitted  for  slow 
motion  on  land. 

4.  Crocodilia,  or  Crocodiles,  Alligators,  and  Gavials. 
(Fig.  153.)  These  are  the  largest  Reptiles.  They  have 
a  double  exoskeleton,  one  of  horny  scales,  (epidermic,) 
and  another  of  bony  plates,  (dermal.)  The  bones  of  the 
skull  are  united  by  sutures,  and  the  jaws  are  furnished 
with  numerous  teeth  implanted  in  distinct  sockets. 
Crocodiles  can  be  distinguished  from  Alligators  by  the 
fourth  tooth  on  the  lower  jaw  being  larger  than  the  rest, 
and  by  its  projecting  on  each  side  of  the  snout.  The 
toes  of  Gavials  and  Crocodiles  are  fully  webbed,  but 
those  of  Alligators  are  only  half- webbed.  Some  Croco- 
diles in  the  Nile  attain  to  a  length  of  twenty-five  feet. 


256 


THE  SCIENCE  OF  LIFE. 


The  Gavials,  or  Crocodiles  of  the  Ganges,  have  the  jaws 
produced  to  an  enormous  length. 

5.  CLASS  IV.  AVES,  or  Birds,  are  warm-blooded  Ver- 
tebrates, clothed  with  feathers. 

The  bones  of  Birds  are  very  compact  and  ivory-like, 
yet  lighter  than  those  of  Reptiles  or  Mammals.  Many 


FIG.    153.  —  i.    Crocodile,    {Crocodilus   vulgaris^     2.    Alligator,   {Alligator  lucius.) 
3.  Lizards. 

parts  of  the  skeleton  are  fused,  or  anchylosed  together. 
The  lumbar  vertebrae  are  wanting,  but  the  neck  con- 
tains from  nine  to  twenty-four  vertebrae,  rendering  it 
quite  flexible.  The  sternum  is  strong,  and  in  birds  of 


VERTEBRATA.  257 

flight  possesses  a  median  Keel,  (carina^)  to  afford  an 
increase  of  space  for  attachment  of  the  great  pectoral 
muscles.  Hence  these  birds  are  called  carinatce.  The 
skull  articulates  with  the  spine  by  a  single  condyle,  and 
with  the  lower  jaw  by  the  intervention  of  a  separate 
bone,  as  in  Reptiles. 

The  beak  is  the  bird's  principal  organ  of  prehension, 
and  differs  in  shape  according  to  habits  and  food.  The 
pharynx  is  simple.  The  oesophagus  varies  in  different 
orders.  Except  in  some  aquatic  birds,  the  food  is  re- 
ceived first  into  a  temporary  stomach,  or  crop,  which  is 
largest  in  grain-feeders.  From  this  the  oesophagus  leads 
to  the  true  digestive  stomach,  which  secretes  the  gastric 
juice,  (proventricidusl)  and  leads  to  the  muscular  stom- 
ach or  gizzard,  (yentriculus  bulbosus.) 

In  tlesh-feeders  this  is  thin,  but  in  grain-feeders  it  is  a 
powerful  triturating  organ.  The  small  intestine  is  short 
in  carnivorous  birds  and  long  in  others.  The  large  in- 
testine ends  in  a  dilated  sac,  the  cloaca,  which  also  re- 
ceives the  terminations  of  the  urinary  and  generative 
organs. 

The  trachea  is  furnished  with  two  larynges  ;  one  at 
the  upper  part,  as  is  usual  in  animals,  and  one  called  the 
syrinx,  which  is  the  principal  organ  of  voice,  at  the  bi- 
furcation of  the  trachea  into  the  two  bronchi.  Every 
means  are  employed  to  render  the  respiration  rapid  and 
complete.  The  lungs  are  large  and  cellular,  and  the 
bronchial  tubes  not  only  divide  continuously  in  them, 
but  conduct  air  into  the  general  cavity  of  the  abdomen 
and  to  the  interior  of  many  of  the  bones. 

The   feathers   of  birds  are  cutaneous   growths,   each 


0¥  TEB 

'UHIVE? 


258 


THE  SCIENCE  OF  LIFE. 


formed  on  a  vascular  papilla  at  the  bottom  of  a  pit,  or 
follicle.  They  are  composed,  like  hair,  of  epithelial  cells. 
Each  feather  consists  of  a  quill,  or  barrel,  and  a  vane,  or 
beard,  which  is  composed  of  barbs  and  barbules.  The 


FIG.  154.— A.  Ear  coverts.    B.  Bastard  wing.     C.  D.  E.  Wing  coverts.     F.  Primaries. 
G.  Scapulars.     H.  Secondaries.     L.  Tail  coverts. 

barbules,  from  contiguous  barbs,  hook  into  each  other 
like  the  latch  of  a  door  into  its  catch,  so  as  to  present  an 
even  and  resisting  surface  to  the  air.  Feathers  receive 
different  names  on  different  parts  of  the  bird's  body. 
The  feathers  clothing  the  body  are  called  clothing  feath- 


VERTEBRATA. 


259 


ers  ;  the  great  quill  tail  feathers,  so  useful  in  steering 
are  the  rectrices ;  those  lying  over  the  humerus  and 
scapular  are  the  scapulars;  the  proximal  end  of  the 
ulna  is  covered  with  the  tertiarics  ;  the  distal  end  of  the 
same  bone  with  the  secondaries ;  while  the  bones  of  the 
hand  support  the  primaries,  which  are  largest  of  all. 
Each  quill  often  carries  a  little  light  feather  just  beneath 
the  commencement  of  the  vane,  the  accessory  plume,  or 
plumule.  These  form  the  greater,  lesser,  and  under 
wing  coverts.  (Fig.  154.) 

Order  I.  Natatorcs,  or  Swimmers.  These  have  the 
body  boat-shaped,  and  the  feet  more  or  less  webbed. 

One  division  of  swimming  birds  is  called  Brevipinnata, 
(Short-wings,)  the  feathers  and  wings  being  short.  It 


FIG.  155. — Common  Tern. 


includes  the  Penguins,  Grebes,  Puffins,  Guillemots,  and 
Divers.      In  the   Penguins  the  wings  are  too  short  for 


260 


THE  SCIENCE  OF  LIFE. 


flight.  The  legs  are  placed  far  back,  and  the  wings 
assist  the  webbed  feet  as  paddles. 

The  Cormorants,  Pelicans,  Gulls,  Petrels,  and  Terns 
(Fig.  155)  form  the  group  of  Longipinnatce,  or  Long- 
wings.  The  beak  is  hooked  and  pointed,  the  tip  being 
often  very  hard.  The  Albatross,  one  of  the  largest  and 
most  beautiful  birds  of  flight,  belongs  to  this  group. 

The  Lamellirostres,  or  Flat-bills,  form  a  third  division, 
including  Ducks,  (Fig.  156,)  Geese,  Swans,  and  Flamin- 


t 


FIG.  156.— Wild  Duck,  (Anas  l>oschas.)    North  America. 

goes,  whose  bills  are  horizontally  compressed,  coverec 
with  a  soft  cuticle  supplied  with  twigs  from  the  fifth 
nerve,  and  have  fringed  sides,  which  strain  the  muddy 
food. 

Order  2.  Grallatores,  or  Waders,  (grallce,  stilts,)  have 
long,  stilt-like  legs,  toes  free,  wings  large  and  powerful. 


VERTEBRATA. 


261 


The  Rails,  Coots,  Water-hens,  and  Jacanas  form  a 
group  called  Macrodactylce,  because  the  claws  are  very 
long.  They  are  four  in  number,  and  lobed.  The  beak 
is  somewhat  cuneiform,  and  the  tail  is  very  short. 

The  Cultirostres,  with  elongated  forcep-like  bills  for 
fishing,  include  the  Cranes,  Herons,  (Fig.  157,)  Stilts, 


FIG.  157. — Heron. 

Ibis,  and  Spoonbills.  The  legs  are  very  long,  and  not 
covered  with  feathers. 

The  Longirostres,  or  Long-beaks,  possess  long  and 
sensitive  beaks,  grooved  by  nostrils.  The  legs  are  of 
moderate  length.  They  are  insectivorous.  The  group 
comprises  the  Snipes,  Woodcocks,  Sandpipers,  Curlews, 
Ruffs,  and  Godwits. 

The  Plovers,  Lapwings,  Bustards,  Longshanks,  and 
Oyster-catchers  form  the  Pressirostres.  All  possess  a 


262  THE  SCIENCE  OF  LIFE. 

moderate  bill  with  a  compressed  tip.  Feet  semi-pal- 
mate, wings  long  and  strong. 

Order  3.  Cursores,  or  Runners.  The  wings  are  rudi- 
mentary and  unfit  for  flight.  The  legs  are  hollow, 
strong,  and  long.  The  order  includes  the  Ostriches, 
Cassowaries,  and  Apteryx,  marked  by  their  large  size, 
keelless  breastbone,  and  robust  legs.  The  African  Os- 
trich has  two  toes,  the  Cassowary  three,  and  the  Ap- 
teryx four.  The  barbs  of  the  feathers  are  disconnected, 
forming  plumes. 

Order  4.  Rasorcs,  or  Gallinac.ece,  Scratchers,  or  Fowls. 
(Fig.  158.)  These  have  a  short  arched  bill,  and  short 


FIG.  158.— Turkey,  (Meleagris  Gallopavo.) 

and  concave  wings.  There  are  three  anterior  toes  and 
one  posterior.  The  anterior  are  blunt  and  adapted  to 
scratching.  The  gizzard  is  very  strong.  The  legs  are 
usually  feathered  to  the  heel,  and  sometimes  to  the 
toes.  The  males  have  usually  gay  plumage  and  some 


VERTEBRATA 


263 


appendage  to  the  head.  Their  principal  food  is  grain. 
The  order  comprises  the  common  Fowl,  Turkey,  Par- 
tridge, Grouse,  Pheasant,  Ptarmigan,  and  Pea-fowl. 

The  preceding  orders  form  a  legion  called  Autopliagi, 
since  immediately  on  being  hatched  they  can  run  about 
and  look  after  themselves.  The  remaining  orders  form 
the  legion  Heterophagi,  in  which  the  young  are  depend- 
ent upon  their  mother  for  nourishment  for  some  time 
after  birth. 

Order  5.  Columbce,  or  Pigeons.  These  differ  from  the 
Scratchers  in  possessing  powerful  wings.  They  have 
slender  legs,  with  toes  ununited,  and  the  hind  toe  on  a 


P'iG.  159.— Wood-Pigeun. 

level  with  the  rest.     Pigeons,  Doves,  (Fig.  159,)  and  the 
extinct  Dodo  are  found  in  this  order. 

Pigeons  exhibit  in  a  great  degree  the  mutability  of 
races    or   varieties ;    all    the  vast    number   of    Pigeons, 


264  THE  SCIENCE  or  LIFE. 

Carriers,  Tumblers,  and  Fantails,  being  descended  fioin 
one  common  stock  —  the  blue  rock  Pigeon,  Colmnba 
livia. 

Order  6,  Scansores,  or  Climbers,  have  four  toes,  two 
directed  forward  and  two  backward.  They  feed  on  in 
sects  or  fruit.  They  are  not  usually  musical.  The 
majority  make  nests  in  the  hollows  of  old  trees,  but  the 
Cuckoos  lay  in  the  nests  of  other  birds.  In  climbing, 
the  Woodpeckers  arc  aided  by  their  stiff  tail,  and  the 
Parrots  by  their  hooked  bill.  Cuckoos,  Parrots,  Toucans, 
Trogons,  Woodpeckers,  and  Wrynecks  belong  to  this 
order. 

Order  7.  ftissrn's,  or  Perchcrs,  is  the  most  numerous 
of  all  the  orders.  The  t\vo  outer  toes  are  joined  by 
membrane.  Of  the  two  others,  one  is  always  directed 
backward.  Females  are  generally  smaller  than  males, 
and  have  more  somber  colors.  Their  nests  arc  often  01 
beautiful  construction.  The  voice  is  often  musical,  the 
plumage  lustrous,  and  the  power  of  flight  perfect. 

The  ConirostrcSy  (Cone-bills,)  with  a  short,  strong, 
roundish  or  conical  beak,  which  tapers  rapidly  from  a 
broad  base  to  a  short  tip,  includes  the  Finches,  with  the 
Sparrows,  Larks,  Crossbills,  Crows,  and  Hornbills.  Birds 
of  Paradise,  also,  and  many  migratory  birds,  as  the  Star- 
ling, belong  here. 

The  Shrikes,  Fly-catchers,  Nightingales,  Orioles,  Rob- 
ins, Thrushes,  Tits,  and  Warblers  form  another  group, 
the  Dcntirostrcs,  or  notched-beaks,  from  having  an  ab- 
rupt notch  on  the  margin  of  the  upper  beak,  near  its 
tip. 

The  Humming-birds,  Hoopoes,  Wrens,  Creepers,  and 


VERTEBRATA.  265 

Honey- eaters,  constitute  the  Tennirostres,  (Slender- 
beaks,)  in  which  group  the  beak  is  elongated  into  a 
slender  forceps  for  extracting  honey  or  insects  from  the 
deep  parts  of  flowers.  The  plumage  is  often  of  a  gor- 
geous metallic  luster. 

The  Swallows,  (Fig.  160,)  Martins,  Goatsuckers,  King- 
fishers, and  Swifts,  make  up  the  Fissirostrcs,  (Cleft-beaks,) 


FIG.  1 60.— Swallow,  (Hirundo.} 

with  a  wide  but  short  beak.  During  flight  the  mouth  is 
kept  wide  open,  and  any  insects  it  encounters  are  re- 
tained by  a  viscid  secretion.  A  young  Swallow  will  in 
this  way  consume  over  a  thousand  flies  and  gnats  in  a 
day. 

Order  8.  Raptores,  or  Raveners.  These  are  readily 
recognized  by  their  beak,  which  is  a  formidable  weapon 
with  sharp  edges  and  an  acute  hooked  tip.  The  upper 
bill  overlaps  the  lower.  The  toes  are  three  in  front 

and  one  behind,  all  terminated  by  sharp  hooked  talons. 
23 


266 


THE  SCIENCE  OF  LIFE. 


Wings,  very  large  and  powerful.    Legs,  short,  stout,  and 
strong. 


^f 

•O 
- 


FIG.  161.— Golden  Eagle. 

There  are  two 
sections:  theDiur- 
nal,  whose  bright 
eyes  are  on  the 
^f>  sides  of  the  head, 
wings  pointed,  and 
metatarsus  and 
\  toes  covered  with 
scales,  as  Vultures, 
Kites,  Hawks,  Fal- 
cons, and  Eagles, 
(Fig.  161 ;)  and  the 
Nocturnal,  whose 
large  eyes  are  di- 
rected forward,  and  surrounded  with  radiating  feathers, 
metatarsus  feathered,  plumage  soft,  as  Owls.  (Fig.  162.) 


FIG.   162.— Barn  Owl. 


VERTEBRATA.  .267 

6.  CLASS  V.  MAMMALIA,  or  Mammals.  These  are  warm- 
blooded Vertebrates  possessed  of  mammary  glands.  They 
suckle  their  young.  The  thorax  and  abdomen  are  sepa- 
rated by  a  diaphragm,  the  red  corpuscles  of  the  blood 
are  doubly  concave  and  round,  (except  in  the  Camel  and 
the  Llama,)  and  either  a  part  or  all  of  the  body  is  hairy. 

All  Mammals  use  their  lips  for  prehension,  which  are 
assisted  in  some  orders  by  their  fore-limbs.  The  Car- 
nivora  tear  their  prey  with  their  claws,  but  do  not  use 
them  as  prehensile  organs.  The  proboscis  of  the  Ele- 
phant, the  snout  of  the  Tapir,  the  long  viscid  tongue  of 
the  Ant-eater,  and  the  long  tongue  of  the  Giraffe,  are 
special  prehensile  organs. 

The  teeth  of  Mammalia  differ  in  the  different  orders, 
as  to  number,  size,  and  shape.  The  true  Ant-eater  has 
no  teeth,  the  Narwhal  has  but  two,  one  of  which  is  rudi- 
mentary, but  the  Dolphin  has  one  hundred  and  ninety. 
The  Whalebone-whale  (Balcena  mysticetus)  has,  instead 
of  true  teeth,  a  series  of  plates  of  whalebone  ranged  in 
rows  along  the  upper  jaw.  From  these  plates  a  long 
fringe  of  whalebone  threads  hangs  down,  which  acts  as  a 
sieve  in  straining  the  water  from  the  myriads  of  little 
mollusca  which  constitute  the  chief  food  of  the  whale. 

There  are  three  distinct  types  of  stomach  among 
Mammals :  the  simple,  the  compound,  and  the  complex 
stomach.  The  simple  stomach  is  a  single  cavity  lined 
by  epithelium,  which  secretes  gastric  juice.  The  com- 
pound stomach  has  the  cavity  divided  by  folds  into  two 
or  more  spaces.  The  tissue-elements,  however,  are  the 
same  throughout.  The  complex  stomach  is  peculiar  to 
the  Ruminants.  It  consists  of  four  cavities:  the  paunch 


268  THE  SCIENCE  OF  LIFE. 

— which  is  the  largest  cavity  of  all — to  store  the  food  and 
mix  it  with  the  water  it  contains,  and  which  in  Camels, 
Llamas,  and  Dromedaries  contains  pits  closed  by  mus- 
cular rims  for  storing  up  fluid  when  the  animal  is  going 
a  long  arid  journey ;  the  reticulum,  or  honey-comb  apart- 
ment, where  the  food  is  made  into  small  round  pellets, 
to  be  regurgitated  into  the  mouth,  where  they  undergo 
a  second  mastication  ;  the  manyplies,  with  its  mucous 
membrane  arranged  in  parallel  folds,  like  the  leaves  of  a 
book,  and  where  some  digestion  of  soluble  parts  of  the 
food  may  occur ;  and  the  rennet,  or  true  digestive  stom- 
ach, where  the  albuminous  principles  of  the  food  are 
extracted  and  absorbed  by  the  veins. 

The  digestive  canal  is  much  longer  in  herbivorous  than 
in  carnivorous  Mammals,  being  thirty  times  the  length 
of  the  animal  in  the  sheep,  and  five  times  the  length  in 
the  cat  and  dog. 

An  external  ear  is  rarely  absent ;  the  eyes  are  always 
present,  though  rudimentary  in  some  burrowing  animals; 
and,  while  in  all  other  animals  the  embryo  is  developed 
from  the  nourishment  contained  in  the  egg,  in  Mammals 
it  derives  its  support,  almost  from  the  beginning,  direct- 
ly from  the  parent,  and,  after  birth,  is  sustained  for  a 
time  by  the  milk  secreted  by  the  mammary  glands. 

Order  I.  Monotremata.  Includes  two  singular  forms, 
the  Duck-mole,  (Ornithorhynchusl)  arid  Spiny  Ant-eater, 
(Echidna?)  both  confined  to  Australia.  The  former  has 
a  fur  covering,  a  bill  like  a  Duck,  and  webbed  feet.  The 
latter  is  covered  with  spines,  has  a  long,  toothless  snout, 
like  the  Ant-eaters,  and  the  feet  are  not  webbed.  Both 
burrow,  and  feed  upon  insects. 


VERTEBRATA. 


269 


Order  2.  Marsupiala,  (marsupos,  a  pouch,)  comprises 
Kangaroos,  Phalangers,  Wombats,  and  Opossums,  (Fig. 
163.)  Except  the  latter,  all  are  restricted  to  Australia 


FIG.  163. — Virginian  Opossum. 

and  adjacent  islands.  The  young  are  always  born  pre- 
maturely, and  are  transferred  by  the  mother  to  a 
pouch  on  the  abdomen,  where  they  are  attached  to  the 
nipples,  and  the  milk  is  forced  into  their  mouths  by 
special  muscles. 

Order  3.  Edentata,  (toothless.)  This  order  contains 
very  diverse  forms,  as  the  leaf-eating  Sloths  and  the  in- 
sectivorous Ant-eaters  and  Armadillos  (Fig.  164)  of  South 
America,  and  the  Pangolin  and  Orycteropus  of  the  Old 
World.  The  gigantic  fossils  Megatherium  and  Glypto- 
don  belong  here.  The  Sloths  and  Ant-eaters  are  cov- 
ered with  coarse  hair;  the  Armadillos  and  Pangolins  with 
an  armor  of  plates,  or  scales.  The  Ant-eaters  and  Pan- 
golins are  strictly  edentate,  or  toothless ;  the  rest  have 
23* 


2/0 


THE  SCIENCE  OF  LIFE. 


molars,    sometimes    very  numerous,   wanting,  however, 
enamel  and  roots. 


I  IG.  164. — Armadillo. 

Order  4.  Rodent  ia,  (gnawers.)  These  have  two  long 
curved  incisors  in  each  jaw,  which  serve  for  gnawing  the 
bark  of  trees,  or  other  substances  on  which  the  Rodent 
feeds.  The  front  only  is  covered  with  enamel,  and  the 

rest  of  the  tooth  is 
composed  of  softer 
dentine,  which, 
wearing  faster  than 
enamel,  leaves  a 
chisel-like  edge  to 
the  tooth.  Canine 
teeth  are  wanting, 

FIG.  i6S.-skuii  of  Rodent.  and  the  flat  molars 

are  separated  from  the  incisors  by  a  wide  interval.  (Fig. 
165.)  The  hind  legs  of  many  Rodents,  as  the  Hare  and 
Jerboa,  are  much  longer  and  stronger  than  the  fore-legs. 
Most  of  the  order  are  small  in  size,  except  the  Capy- 


VERTEBRATA.  271 

bara,  Beaver,  and  Porcupine.  The  order  also  contains 
Squirrels,  Rats,  Mice,  and  Agoutis.  The  Beaver  has  a 
smooth,  unconvoluted  brain,  yet  shows  great  ingenuity 
in  constructing  its  dwelling,  felling  logs  with  its  teeth, 
building  them  into  a  dam,  and  arranging  others  as  a 
shelter,  plastering  them  with  mud  made  into  mortar  by 
its  flat,  trowel-like  tail.  The  Flying-squirrel  (Pteromys) 
possesses  a  cloak  of  skin,  stretching  between  the  fore  and 
hind  limbs,  enabling  it  to  sustain  short  flights  in  the  air. 

Order  5.  Insectivora,  (insect-eating.)  These  are  di- 
minutive animals,  as  the  Shrew,  the  Hedgehog,  and  the 
Mole.  They  have  incisor,  canine,  and  molar  teeth,  and 
the  latter  have  numerous  pointed  cusps.  They  have  a 
long  muzzle,  short  legs,  and  clavicles.  The  feet  are 
formed  for  walking  or  grasping,  and  are  plantigrade, 
five-toed,  and  clawed.  The  Hedgehogs  have  a  spiny 
exoskeleton,  covering  the  entire  body,  and  lined  by  a 
broad  muscle,  which,  when  it  contracts,  rolls  the  animal 
into  a  ball. 

Order  6.  Cheiroptera,  (cheir,  a  hand ;  pteron,  a  wing,) 
are  distinguished  by  long  fore-limbs,  adapted  for  flight, 
the  fingers  being  very  long,  and  united  by  a  membra- 
neous web.  The  toes  and  one  or  two  of  the  fingers  are 
armed  with  hooked  nails.  The  Bat  may  be  called  the 
only  true  flying  Mammal,  since  it  is  capable  of  rapid 
and  long-continued  flights.  (Fig.  166.)  The  Vampire- 
bat  has  a  curious  leaf-like  expansion  of  the  skin  cover- 
ing the  nose.  The  ears  of  Bats  are  very  large,  and 
copiously  supplied  with  nerves  of  touch.  The  sense  of 
hearing  is  also  acute. 

Order  7.  Cetacea,  (Ketos,  a  whale,)  are  fish-like  in  form 


272  THE  SCIENCE  OF  LIFE. 

and  habits.     They  are  the  largest  of  all  living  forms, 
and,  next  to   the   Elephant,  have  the  heaviest  brains. 


FIG.  166.— The  Skeleton  of  Bat.  cl.  Clavicle,  h.  Humerus.  cu.  Ulna.  c.  Radius. 
ca.  Carpus.  j>o.  Thumb,  -me.  Metacarpus,  ph.  Phalanges,  o.  Scapula,  f.  Femur. 
ti.  Tibia. 

The  nostrils  are  on  the  top  of  the  head,  and  constitute 
the  blow  holes,  or  spiracles.  This  order  includes  the 
Whales  and  Dolphins.  All  have  a  large  horizontally 
flattened  caudal  fin.  The  head  is  large,  often  forming 
half  the  bulk  of  the  animal.  The  Whalebone  Whales 
(BalcsnidcB)  are  toothless,  but  in  the  Greenland  Whale, 
the  largest  of  the  group,  which  sometimes  attains  a 
length  of  sixty  or  seventy  feet,  we  find  rudimentary 
teeth  in  the  embryo.  The  Toothed  Whales  (Odontoceti) 
have  many  conical  teeth  in  the  lower  jaw.  The  Sperm 
Whales  are  in  this  division.  In  them  the  head  is  large 
and  abruptly  truncated,  and  the  nostrils  are  at  the  end 
of  the  muzzle.  The  Delphinida,  comprising  the  Dol- 
phins, Narwhals,  and  Porpoises  have  teeth  in  both  jaws. 
Many  Cetacea  have  very  small  organs  of  smell,  and  in 
the  Dolphins  and  Porpoises  they  are  wanting. 


VERTEBRATA.  273 

Order  8.  Sirenia  (seiren,  a  siren,  or  Mermaid)  are  like 
the  Cetacea  in  shape,  but  are  herbivorous,  and  frequent 
great  rivers  and  estuaries.  They  have  both  a  temporary 
and  permanent  set  of  teeth,  a  narrow  brain,  and  nostrils 
on  the  top  of  a  large  snout.  The  Dugong  and  Manatee 
are  illustrations  of  this  order. 

Order  9.  Proboscidia  include  the  Elephant,  the  extinct 
Mastodon,  the  Dinothere,  and  the  Mammoth.  There 
are  no  canine  teeth,  but  the  incisors  are  prolonged  into 
tusks,  which  in  the  Elephant  grow  from  the  upper  jaw, 
in  the  Dinothere  from  the  lower  jaw,  and  in  the  Masto- 
don from  both  jaws.  The  nose  is  prolonged  into  a  long, 
flexible,  sensitive  trunk,  which  is  terminated  by  a  small 
prehensile  appendage  like  a  finger.  Cuvier  counted 
20,000  distinct  muscles  in  an  Elephant's  trunk.  The 
limbs  are  massive,  each  with  five  toes  incased  in  hoofs, 
and  with  a  thick  pad  intervening  between  the  toes  and 
the  ground. 

Order  10.  Ungulata,  or  Hoofed  Quadrupeds,  have 
four  well-developed  limbs,  each  having  not  more  than 
four  complete  toes,  and  each  toe  being  incased  in  a  hoof. 
The  leg  is  therefore  for  support  and  motion,  and  not  for 
prehension.  They  have  temporary  and  permanent  sets 
of  teeth.  The  Odd-toed  Ungulates  include  the  Horse, 
the  Rhinoceros,  and  the  Tapir.  The  Horse,  which 
with  the  Ass  and  Zebra,  made  up  the  old  order  of  Soli- 
dungula,  has  only  a  single  perfect  toe  on  each  foot, 
coated  with  a  nail,  called  a  hoof,  so  that  the  horse  walks 
and  runs  not  merely  on  its  toes,  but  on  its  nails.  The 
Rhinoceros  has  three  toes  on  each  foot,  and  carries  one 
or  two  horns  on  the  skin  of  the  nose. 


274 


THE  SCIENCE  OF  LIFE. 


The  Tapir  has  four  toes  on  its  fore  feet,  and  three  on 
its  hind  feet,  a  short  snout,  projecting  nasal  bones,  and 
a  short  tail. 

The  Even-toed  Ungulates — the  Hog,  Hippopotamus, 
and  Ruminants — have  two  or  four  toes.  The  Hog  and 
Hippopotamus  have  the  four  kinds  of  teeth :  incisors, 
canines,  bicuspids,  (or  premolars,)  and  molars,  and  in  the 


FIG.  167. — Stag. 

wild  state  are  vegetarian.  The  Ruminants  have  two 
toes  on  each  foot,  enveloped  in  hoofs  which  face  each 
other  by  a  flat  side,  so  as  to  appear  like  a  single  hoof 
split,  or  cloven.  There  may  be  two  supplementary 
hoofs  behind,  but  they  do  not  usually  touch  the  ground. 
All  chew  the  cud  and  have  a  complicated  stomach. 
They  have  incisors  in  the  lower  jaw  only,  and  these  are 


VERTEBRATA.  275 

apparently  eight ;  but  the  two  outer  ones  are  canines. 
With  few  exceptions,  as  the  Camel,  all  Ruminants  have 
horns,  which  are  in  pairs.  Those  of  the  Deer  (Fig.  167) 
are  solid,  bony,  and  deciduous ;  those  of  the  Giraffe 
and  Antelope  are  solid,  horny,  and  permanent ;  in  the 
Goat,  Sheep,  and  Ox  they  are  hollow,  horny,  and  per- 
manent. 

Order  II.  Carnivora,  or  Beasts  of  Prey,  have  four 
long,  acute,  canine  teeth,  and  there  is  a  gap  between 
the  incisors  and  canines  of  the  upper  jaw  for  the  recep- 
tion of  the  lower  canine.  There  are  usually  six  incisors 
in  each  jaw.  The  digits  always  have  sharp  and  pointed 
claws.  The  body  is  cov- 
ered with  hair. 

The  order  is  divided 
according  to  the  pecu- 
liarities of  the  limbs. 
(Fig.  168.) 

The  Pinnigrada  com- 
prise the  Seals  and  Wal- 
ruses. The  fore  feet  are 
webbed  and  form  pad- 

fir,.    1(^8. —  I  oe  of  Lion.     a.  With  the  claw 

dleS          The    hind     feet    are      exte»ded.       />.  c.  Without   the  skin,  retracted 

and  extended. 

at  the  end  of  the  body, 

enveloped  in  the  integument,  and  in  action  they  resem- 
ble the  screw  of  a  steam-ship.  They  live  on  fish. 

The  Plantigrada  have  the  whole,  or  nearly  the  whole, 
of  the  hind  foot  in  the  form  of  a  sole,  which  rests  on  the 
ground.  The  claws  are  not  retractile  ;  the  ears  are  small, 
and  tail  short.  Bears,  Badgers,  and  Raccoons  are  well- 
known  examples. 


276 


THE  SCIENCE  OF  LIFE. 


Digitigrada  walk  on  the  tips  of  the  toes,  and  keep  the 
heel  raised  above  the  ground.  It  includes  the  fierce  and 
powerful  Cats,  Pole-cats,  Ferrets,  Weasels,  Dogs,  Hy- 
aenas, Jackals,  Otters,  etc.  The  Cats,  (Felidce^)  embracing 
Lions,  (Fig.  169,)  Tigers,  Leopards,  Panthers,  and  Cat;-, 


Fir,.  j^o.— Skeleton  of  the  Lion,  (Fells  I.co^  C.  Cervical  vertebrae.  D.  Dorsal  verte- 
bra:. L.  Lumbar  vertebra.  S.  Sacral  vertebrae.  C.  d.  Caudal  vertebrae,  a.  Scapula. 
b.  Humerus.  c.  Ulna.  d.  Radius,  e.  Metacarpus  and  phalanges,  f.  Ilium,  g.  Femur. 
h.  Ischium.  /.  Patella,  k.  Tibia.  /.  Fibula,  m.  Tarsus,  n.  Os  Calcis.  o.  Metatarsus 
and  phalanges. 

have  retractile  claws,  and  the  radius  rotates  freely  on  the 
ulna.  They  have  also  a  prickly  tongue. 

Order  12.  Quadrnmana  (four-handed)  differ  from  all 
other  Mammals  by  having  each  of  their  four  limbs  termi- 
nated by  hands,  in  which  the  thumb  is  opposable  to  the 
other  digits.  (Fig.  170.) 

The  order  is  subdivided  according  to  the  position  of 
the  nostrils,  into  I.  Strepsirhines,  or  Monkeys  with 
twisted  nostrils,  as  the  Lemurs  and  Aye-ayes,  which 


VERTEBRATA.  277 

are  the  lowest  of  the  monkey  tribe.  2.  Platyrrhines,  or 
Monkeys  with  simple  sub-terminal  nostrils,  as  the  Spider- 
monkeys.  These  are  South  American,  or  New- World 
monkeys,  with  prehensile  tails.  The  Howling-monkey 
(Mycetes)  has  a  curious  modification  of  the  larynx  in  the 
shape  of  a  bony  drum  attached  to  the  hyoid  bone,  with 
which  it  produces  discordant  shrieks.  3.  Catarrhines,  or 


FIG.  170. — Quadrumana.  Baboons. — i.  Mandrill,  (Papio  maimon.)  2.  Chacma,  (Chac- 
ma  Porcarius.)  Monkeys. — 3.  Mona,  (Cercopithecus  mono,.}  4.  Howler,  (Mycetes.) 
5.  Spider,  (A  teles.) 

monkeys  with  oblique  nostrils,  approximating  below, 
separating  above,  as  the  Gorilla  and  Chimpanzee.  This 
division  includes  the  highest,  or  anthropoid  Apes  of  the 

Old  World.    They  are  all  four-thumbed.    The  tail  is  not 
24 


278 


THE  SCIENCE  OF  LIFE. 


prehensile,  and  is  often  quite  rudimentary.  The  canine 
teeth  are  large.  (Fig.  171.)  The  arms  are  long;  in  the 
Chimpanzee  reaching  to  the  middle  of  the  tibia,  when 
hanging  down. 


FIG.  171. — A.  Slcull  of  the  Orang-outang.     B.  Skull  of  an  ndult  European. 

Order  13.  Biwana,  (two-handed,)  contains  but  one 
genus  and  one  species:  Homo,  or  Man.  (Fig.  172.) 

Man  differs  from  all  animals  in  being  an  erect  biped. 
The  vertebrate  type,  which  in  all  other  cases  is  horizontal, 
in  him  is  vertical.  No  other  animal  habitually  stands 
erect ;  in  no  other  are  the  fore-limbs  used  exclusively  for 
head  purposes,  and  the  hind  pair  solely  for  locomotion. 
His  limbs  are  parallel  to  the  axis  of  his  body,  not  per- 
pendicular. They  are  nearly  equal  in  length,  but  the 
arms  are  always  a  little  shorter  than  the  legs.  In  the 
Apes  the  arms  reach  below  the  knee. 

Man  only  has  a  finished  hand,  which  is  a  perfect  organ 
of  touch,  and  most  versatile  in  movement.  The  foot  is 
planted  upon  the  ground  by  the  entire  length  of  the  sole. 
The  Gorilla  has  an  inferior  hand  and  an  inferior  foot. 


VERTEBRATA. 


279 


The  hand  is  clumsier  and 
with  a  shorter  thumb  than 
man's,  and  the  foot  is  pre- 
hensile, and  is  not  applied 
flat  to  the  ground. 

Man  is  peculiar  in  his 
dentition.  His  teeth  are 
vertical,  of  nearly  uniform 
height,  and  close  together. 
In  every  other  animal  the 
incisors  and  canines  are 
more  or  less  inclined,  the 
canines  project,  and  there 
are  vacant  spaces. 

Man  possesses  two  mus- 
cles (the  peroneus  tertius 
and  extensor  primi  inter  - 
nodii  pollicis)  which  are  not 
found  in  the  highest  Apes. 
The  origin  of  two  other 
muscles  is  in  Man  alto- 
gether different  from  Apes. 
(The  tibial  origin  for  the 
soleus,  and  the  calcaneal 
origin  for  the  flexor  brevis 
digitorum^) 

The  human  skull  has  a 
smooth  rounded  outline, 
elevated  in  front,  and  de- 
void of  crests.  The  crani- 
um greatly  predominates 


FIG.  172.— The  Human  Skeleton,  a.  Skull. 
b.  b.  Vertebral  column,  or  Spine,  c.  Ribs. 
d.  Sternum,  or  Chest  bone.  e.  e.  Scapulae, 
or  Blade  bones.  f.  /.  Clavicles,  or  Collar 
bones,  g.  g.  Pelvic,  or  Hip  bones,  h,  h.  Hu- 
meri,  or  Arm  bones,  z.  Radius,  and  j.  Ul- 
na, bones  of  fore-arm,  k.  Femur,  or  Thigh 
bone.  /.  Tibia,  or  Large  bone  of  leg.  in.  Fib- 
ula, or  Small  bone  of  leg.  n.  Calcaneum,  or 
Heel  bone.  o.  Tarsal  bones,  or  Bones  of 
the  foot.  /.  Carpal  bones,  or  Bones  of  the 
wrists. 


280  THE  SCIENCE  OF  LIFE. 

over  the  face,  being  four  to  one.  Man  differs  from  all 
Apes  in  the  absolute  size  of  brain,  and  in  the  greater 
complexity  and  less  symmetrical  arrangement  of  its  con- 
volutions. The  brain  of  the  Gorilla  scarcely  amounts 
to  one  third  in  volume  or  one  half  in  weight  of  that  of 
Man. 

From  purely  morphological  reasons,  therefore,  Man  is 
entitled  to  rank  as  a  distinct  order  of  Vertebrates.  Other 
considerations,  to  be  referred  to  in  the  next  chapter, 
show  that  he  should  be  regarded  as  a  distinct  type. 


THE  HUMAN  TYPE.  281 


CHAPTER   XVI. 

THE    HUMAN    T  Y  P  E . 

The  master-work,  the  end 
Of  all  yet  done  ;  a  creature,  who,  not  prone 
And  brute  as  other  creatures,  but  endued 
With  sanctity  of  reason,  might  erect 
His  stature,  and  upright  with  front  serene 
Govern  the  rest,  self-knowing ;  and  from  thence 
Magnanimous,  to  correspond  with  Heaven, 
But  grateful  to  acknowledge  whence  his  good 
Descends;  thither  with  heart,  and  voice,  and  eyes 
Directed  in  devotion,  to  adore 
And  worship  God  Supreme,  who  made  him  chief 
Of  all  his  works.— MILTON. 

1.  IN   the   rapid  panoramic   survey  of  living  forms, 
which  is  all  our  limits  will  allow,  we  have  mainly  con- 
fined ourselves  to  structural  forms,  barely  glancing  at 
the  instinctive  peculiarities  which  determine  these  forms 
for  special  ends.     It  is  necessary  to  supplement  our  re- 
view by  a  reference  to  functions  and  endowments  which 
the  structure  itself  may  not  always  indicate. 

2.  Biology  includes  not  only  Anatomy  and  Physiology, 
but   Psychology  also.     "  The  naturalist  studies  the  in- 
stincts of  the  Ants  and  the  Bees.     When  he  attempts 
the  history  of  Man,  shall  he  put  aside  that  which  in  him 
represents  these  instincts  ?    Evidently  not.    Consequent- 
ly he  must  not  stop  with  the  body.     He  must  consider 
the  intelligence  which  is  in  us,  and  which,  up  to  a  cer- 
tain point,  we  have  in  common  with  animals;  he  must 

show  that  it  is  this  element  of  our  being  which  recog- 
24* 


282  THE  SCIENCE  OF  LIFE. 

nizes  the  outer  world,  which  judges,  which  aspires.  His 
work  will  be  very  imperfect  if  he  neglects  this  some- 
thing of  which  the  nature  escapes  us,  but  of  which  the 
power  is  such,  that  through  it  man  has  not  only  van- 
quished all  animals,  whatever  their  defenses,  their  size, 
or  their  strength,  but  he  has  overcome,  and  made  to 
work  as  his  servants,  even  the  immutable  forces  of  the 
inanimate  world."  * 

3.  We  have  seen  that  the  lower  animals  partake  of 
living  structures  and  organs,  the  same  in  essential  char- 
acter and  objects  as  those  of  man.     Careful  observation 
will  show  that  they  also  possess  many  mental  or  psycho- 
logical endowments,  such  as  we  find  in  the  human  type. 
The  differences  of  animated  nature  are  differences  of 
degree  rather  than  of  essential  nature.     So  far  as  we  can 
see,  all  animals  have  self-consciousness  and  volition,  and 
many  exhibit  unmistakable  signs  of  reason. 

4.  On  page  283  is  an  outline  plan  of  the  psychical  en- 
dowments of  man,  with  the  objects  constantly  influenc- 
ing him  and  the  normal  activities  of  his  being.     It  be- 
gins with  the  most  general  and  elementary  properties 
of  animal  life,  and  rises  to  the  highest  special  powers 
of  human  nature.     More  than  an  outline  cannot  be  at- 
tempted, since  an  elaborate  exposition  would  require  a 
large  volume. 

5.  It  will  be  seen  that  we  have  given  prominence  to 
consciousness  in  the  plan  referred  to.     This  is  because 
it  is  an  essential  condition  of  every  mental  operation. 
It  is  the  knowledge  which  the  mind   has  of  its  own 
operations. 

*  Quatrefage's  "  Natural  History  of  Man." 


'     y>>  0*  TEJ         ^X 

urivsEsiTy) 

c**1   ^**§fjf 

THE  HUMAN  TYPE.  283 

Objective.  SUBJECT.  Subjective. 

g-SJS          Will. 
Spiritual  and  Rational  Ob- 


pintual  and  Rational  Ub-      £  ^  o  Judgment 

jects.  (the  Good,  Beauti-     .2  g  .g  JUflgme 

ful,  True,  etc.)  g  ;|  ^  Faith< 


—  I 
I      I 


|  |  -f  |  Fancy. 

^  The  Mind  itself.  g  S  |  ,        , 

k  .2  g'Ei)  Thought. 

^  w'5  2 


8 

s    g. 

§      Perception. 


•S  Objects  of  Sense.  .2  *g  '^ 

.1  §     c/3  Voluntary  Motion. 

Obscure  Ideas. 


5*  *1 

^  Organic  Sensibility.  2  *o  *o  Instincts,  or  Consensual       § 

§  '£      w  Actions.                               ». 

*  §   5  fe 


=5 
1    ? 

W  VH 

The  Organic  Life.  o  *«  i  Involuntary  Motion. 


284  THE  SCIENCE  OF  LIFE. 

In  the  general  account  of  the  nervous  system  (Chap. 
XV.,  Sec.  i)  it  was  stated  that  many  motions  were  merely 
reflex  and  involuntary.  Many  such  motions  are  also 
without  consciousness.  It  is  probable  that  a  very  large 
proportion  of  the  movements  of  the  lower  animals  are 
of  this  character.  Other  motions  depend  on  organic 
contractility  responsive  to  an  external  stimulus,  as  when 
a  piece  of  muscular  fiber  contracts  on  being  scratched 
with  a  pin.  Ciliary  motions,  the  closure  of  the  leaves  of 
Venus'-flytrap  (Dionaa)  on  being  touched  by  an  insect, 
and  the  movements  of  the  Sensitive  plant,  may  thus  be 
accounted  for.  Some  motions,  as  the  sleep  of  plants, 
depend  on  the  periodicity  of  functional  activities,  and 
others,  as  the  bursting  of  seed-vessels,  may  be  owing  to 
Endosmose.  Mere  movement,  therefore,  is  far  from  in- 
dicating consciousness. 

"  How  early  does  consciousness  arise  ?  If  we  inter- 
pret, as  we  are  constantly  doing,  the  experience  of  lower 
animals  by  that  of  higher  ones,  we  should  answer,  With 
the  very  commencement  of  animal  life.  Indeed,  noth- 
ing but  conventional  sentiment  would  prevent  our  attrib- 
uting, under  this  method,  a  feeble  consciousness  to  some 
plants.  If,  however,  we  reason  from  the  character  of  the 
nervous  system,  which  is  undoubtedly  the  sole  organ  of 
consciousness,  and  from  the  stages  in  development  at 
which  a  conscious  experience  can  enter  as  a  profitable 
factor,  we  shall  be  inclined  to  believe  that  consciousness 
especially  characterizes  the  Vertebrata,  and  appears  first 
in  the  higher  Articulata  and  Mollusca.  The  phenomena 
of  consciousness  undoubtedly  increase  greatly  in  vigor 
and  in  value  as  we  pass  up  through  the  Vertebrata,  and 


THE  HUMAN  TYPE.  285 

this  form  of  activity  is,  in  its  governing  relations,  col- 
lected and  specialized  in  the  cerebrum."  * 

Without  attempting  to  dogmatize  upon  a  subject  so 
imperfectly  known,  we  may  suggest  that  many  of  the 
habits  of  Ants,  Bees,  and  even  of  animals  of  a  more  prim- 
itive type,  afford  as  good  evidence  of  consciousness  as 
the  actions  of  human  creatures  themselves. 

6.  The  consciousness  of  self,  or  general  corporeal  sen- 
sitiveness, is  the  earliest  sign  of  individuality,  or  personal 
knowledge.     This  is  previous  to  the  senses,  and  inde- 
pendent of  the  nervous  system.     It  manifests  itself  in 
animals  without  nerves,  as  the  Polyps,  and  seems  to  be 
a  necessary  attribute  of  animal  life.     Yet  this  most  prim- 
itive and  most  clearly  innate  faculty  implies  mind,  for 
by  it  we  know  that  our  body  is  our  body.     The  corporeal 
structure  is  an  object  of  which  the  mind  takes  cogni- 
zance.    The  presence  of  this  sensitivity  proves  the  ex- 
istence of  something  distinct  from  the  body. 

7.  The  consciousness  of  the   physical  conditions  or 
states  of  the  body — as  tonicity,  languor,  hunger,  thirst, 
warmth,  and  cold — has  been  termed  common  sensation, 
or  coenasthesis.    It  is  especially  conducted,  at  least  in  the 
higher  animals,  by  the  ganglionic  or  sympathetic  sys- 
tem of  nerves.     By  means  of  the  connection  of  this  with 
the  cerebro-spinal  system  the  various  affections  of  the 
mind  and  body  mutually  act  upon  each  other,  rendering 
the  phenomena  quite  complex.     Certain  obscure  ideas, 
of  which  one  may  be  said  to  be  half-conscious,  and  which 
taken  together  make  up  what  we  call  the  disposition  or 
temper  of  a  man,  are  the  result  of  organic  sensibility  act- 

*  Bascom's  "  Comparative  Psychology." 


286  THE  SCIENCE  OF  LIFE. 

ing  upon  the  common  sensation.  What  Dr.  Carpenter 
terms  "  consensual  actions  "  may  also  originate  here,  as 
well  as  from  sensation  proper.  In  this  term  that  emi- 
nent physiologist  includes  "all  the  purely  instinctive  ac- 
tions of  the  lower  animals,  which  make  up,  with  the  u  re- 
flex," nearly  all  the  animal  functions  in  many  tribes,  and 
which  are  peculiarly  elaborate  in  their  character  and 
wonderful  in  their  results  in  Insects.  Such  automatic 
and  involuntary  actions  as  vomiting  excited  by  the  sight 
of  a  loathsome  object,  a  bad  smell,  or  a  disagreeable 
taste,  or  laughter  excited  by  tickling,  are  also  classed 
under  this  term. 

8.  Sensation,  or  special  sense,  is  caused  by  an  impres- 
sion on  certain  parts  of  the  nervous  system,  which  are 
hence   called   sensitive.     For  sensation  two  things  are 
necessary:  an  impressible  state  of  the  sensitive  organs, 
and  a  perception  by  the  mind. 

9.  Perception  is  the  evidence  we  have  of  external  ob- 
jects by  means  of  the  senses.     It  is  necessary  that  the 
organs  and  nerves  be  sound,  or  false  perceptions  will  re- 
sult.    Ringing  noises  in  the  ears,  floating  specks  before 
the  eyes,  and  many  spectral  illusions,  have  their  origin 
in  a  diseased  condition  of  the  organs.     Yet  that  percep- 
tion is  an  attribute  of  mind  is  evident  from  the  fact  that 
attention  is  required.     The  senses  may  be  impressed  by 
their  appropriate  objects,  but  without  attention  they  are 
not  perceived. 

10.  Memory  implies  a  former  conscious  experience, 
either  of  a  physical  or  mental  kind  ;  its  retention,  revival, 
and  recognition.  The  laws  of  memory,  as  they  are  called, 
or  circumstances  which  excite  recollection,  have  been 


THE  HUMAN  TYPE.  287 

enumerated,   as   resemblance,    contiguity,  cause,    effect, 
and  contrast. 

11.  The  mind  itself  may  produce  in  the  sphere  of 
consciousness,  ideas,  sentiments,  emotions,  and  imagina- 
tions.    For  the  manifestation  of  mental  phenomena  it  is 
doubtless  important  to  have  continuously  healthy  nerve- 
structure  and   other  bodily  organs,  since  the  most  ac 
complished  artisan  cannot  exhibit  his  full  powers  with 
imperfect  tools  and  materials ;  yet  as  the  injury  or  de- 
struction of  the  implement  is  no  proof  of  the  annihilation 
of  the  artisan,  so  the  injury  or  even  destruction  of  the 
body  may  not  affect  the  soul.     The  mind  is  popularly 
supposed  to  be  dependent    on   the  brain,   yet   medical 
authorities   show  that   every  portion   of  the   brain  has 
been,  in  one  instance  or  another,  destroyed  or  disorgan- 
ized without  affecting  what  are  supposed  to  be  the  cor- 
responding intellectual  powers.     Abercrombie  tells  of  a 
lady  in  whom  one  half  the  brain  was  disorganized,  but 
who  retained  all  her  faculties  to  the  last,  and  many  such 
instances  are  'on  record.     There  is  no  constant  relation 
between  the  integrity  of  mind  and  body.    The  mind  may 
suffer  intense  agony  while  the  body  is  in  perfect  health, 
or  remain  in  calm  serenity  while  the  body  is  tortured  or 
is  losing  its  vital  powers. 

12.  Ideas,  in  a  general  sense,  refer  to  any  thing  present 
to  the  mind  as  an  object  of  thought,  whether  present 
really  or  representatively.     Some  ideas  are  related  to 
experience,  as  the  principles  of  mathematics,  notions  of 
figure,  extension,  number,  time,  and  space.     Others  are 
independent  of  sensible  representation,  as  the  ideas  of 
good  and  evil,  just  and  unjust,  true  and  false. 


288  THE  SCIENCE  OF  LIFE. 

13.  Sentiments  refer  to  feelings  of  esteem,  gratitude, 
patriotism,  etc.,  but  emotions  to  mental  pleasure  or  pain. 
The   emotions   are   often  very  complex,  and   influence 
every  part  of  the  nature,  physical  and  mental ;  as  hope, 
joy,  melancholy,  love,  and  anger. 

14.  Imagination  is  a  term  which  represents  the  power 
which  the  mind  has  of  combining  ideas.     The  images 
produced  by  this  faculty  are  sometimes  so  vivid  as  to 
affect  the  organs  of  sense,  and  occasion  morbid  sensual 
delusions,  as  well  as  to  influence  the  organs  of  motion, 
secretion,  etc.     No  proof  could  be  more  positive  of  the 
independent  agency  of  the  mind.     In  its  highest  degree 
imagination  leads  to  creative  fancy,  or  poetic  power.     In 
some  of  its  flights  it  may  encroach  upon  the  prerogative 
of  conscience,  and  lead  to  self-deception  unless  held  in 
check  by  the  precepts  of  Divine  revelation. 

15.  Conscience  has  been  called  the  moral  sense,  moral 
faculty,    moral   judgment,    and   susceptibility   of   moral 
emotions.     It  may  also  be  termed  the  inspirational  ca- 
pacity of  the  soul.     It  is  that  faculty,  or  combination  of 
faculties,  by  means  of  which  we  have  ideas  of  right  and 
wrong  respecting  actions,  and  corresponding  feelings  of 
approbation  or  disapprobation.     Faith,  in  the  scriptural 
sense  of  the  term,  is  not  belief,  but  the  volitional  activity 
of  the  mind  in  the  sphere  of  the  conscience, 

16.  Judgment  is  the  decision  of  the  mind  after  com- 
parison.    It  is  altogether  a  mental  function.     It  is  an  act 
of  the  mind  upon  and  within  itself. 

17.  Volition  is  the  dominion  exercised  by  the  mind 
over  itself,  employing  or  withholding  its  faculties  in  any 
particular  action.     It  is  synonymous  with  free  agency, 


THE  HUMAN  TYPE.  289 

and  is  an  essential  attribute  of  spirit,  since  the  very  idea 
of  spirit  supposes  self-action.  Feuchtersleben  judiciously 
distinguishes  between  the  essential  freedom  of  the  spirit 
and  the  freedom  of  the  spirit  linked  to  the  body.  He 
shows  that  freedom  may,  first,  limit  itself,  so  far  as  the 
spirit  makes  itself  the  slave  of  sin  or  error;  second,  it  may 
be  limited  by  physical  laws ;  third,  it  may  be  limited  by 
organization.  As  to  the  first,  the  free  man  is  good  and 
wise ;  as  to  the  second,  powerful;  as  to  the  third,  healthy. 

1 8.  This   brief  examination  of  human    endowments 
shows  as  great  a  difference  between  men  and  brutes  as 
exists  between  animals  and  vegetables,  or  between  vege- 
tables and  the  mineral  world.     It  is  considered  by  many 
that  each  department  of  nature  becomes  higher  through 
the  addition  of  something  which  the  next  below  it  did 
not  possess,  and  as  the  differences  of  the  animal  and 
vegetable  world  form  successive  additions  to  a  common 
original  plan  or  system  of  organization,  we  find  fore- 
shadowings  or  prophecies  of  the  characteristics  of  higher 
forms.     Thus  the  regularity  of  the  crystal  suggests  to 
the  imagination  the  organization  of  the  plant,  and  the 
motions  of  plants  foreshadow  the  nervous  system.    Thus, 
too,  the  higher  animals  have  vague  and  indistinct  analo- 
gies of  the  vast  endowments  of  man. 

19.  The  unity  of  man  was  generally  conceded  by  the 
early  naturalists,  but  has  been  largely  debated  in  recent 
times.     Agassiz  himself  held  to  different  creations,  al- 
though believing  they  were  a  unit  as  to  intellectual  and 
moral  nature.      The  discussion  continued,   until   a  few 
years  ago  it  appeared  to  be  the  settled  creed  of  men  of 

"advanced"  views  to  deny  man's  unity.     Yet  one  point 
25 


290  THE  SCIENCE  OF  LIFE. 

after  another  has  been  changed,  until,  in  the  language 
of  Mr.  Tylor,*  "  it  may  be  asserted  that  the  doctrine  of 
the  unity  of  mankind  now  stands  on  a  firmer  basis  than 
in  any  previous  ages." 

20.  Respecting  the  antiquity  of  man  upon  the  earth, 
it  is  very  plain  that  the  differences  between  the  Hebrew, 
Samaritan,  and  Greek  Pentateuch  are  such  as  to  forbid 
any  settlement  of  the  question   by  a  reference  to  the 
Scriptures.    Long  before  the  modern  discussions  on  this 
subject  biblical  scholars  doubted  if  it  was  the  design  of 
the  Scriptures  to  reveal  either  the  antiquity  of  man  or 
the  age  of  the  earth.     Yet  the  discovery  of  human  re- 
mains at  Abbeville  and  other  places,  the  remains  of  lake- 
dwellings  in  Switzerland,  and  the  shell  heaps  in  Den- 
mark,   are    nowise    inconsistent    with    the    view    of    a 
degradation  of  some  races  from  a  more  highly  civilized 
condition.     The  ruins  of  ancient  nations  certainly  point 
to  an  early  civilization  which  was  remarkable  for  extent 
and  splendor.    As  to  the  time  required  for  these  changes, 
Dana,  in  his  "  Manual  of  Geology,"  says:  "  The  evidence, 
as  it  at  present  stands,  does  not  necessitate  the  carrying 
of  man  back  in  past  time,  so  much  as  the  bringing  for- 
ward of  the  extinct  animals  toward  our  own  time." 

21.  The  numerous  varieties  of  the  human  species  may 
be  divided  into  four  principal  races,  which  comprise  sec- 
ondary and  mixed  races,  each  including  a  number  of 
families  and  nations:  1st.  The  White  race,  also,  but  er- 
roneously, called  Caucasian.     Its  original  country,  judg- 
ing from  the  comparison  of  languages  and  historic  testi- 
mony, lay  between  the  Mediterranean,  the  Red  Sea,  the 

*Art.,  Anthropology,  in  Encyc.  Brit.,  ninth  edition. 


THE  HUMAN  TYPE.  291 

Indian  Ocean,  the  steppes  of  Central  Asia,  and  the  Him- 
alaya Mountains.  From  thence  it  has  spread  into  India, 
Arabia,  Syria,  Asia  Minor,  and  Egypt.  2d.  The  Red, 
inhabiting  only  America.  3d.  The  Yellow,  which  has 
existed  in  China  from  remote  antiquity,  and  has  spread 
into  all  countries  inhabited  by  Mongolians.  4th.  The 
Black,  which  belongs  to  Central  and  Western  Africa, 
and  is  distributed  over  the  tropics  from  the  east  coast 
to  Australia.  It  is  doubtful  if  either  of  these  races  rep- 
resents the  primitive  type  of  man. 

22.  We  close  our  brief  survey  of  life  with  the  religious 
sentiments  of  the  Psalmist :  *•  I  will  praise  thee ;  for  I 
am  fearfully  and  wonderfully  made:  marvelous  are  thy 
works ;  and  that  my  soul  knoweth  right  well.  My  sub- 
stance was  not  hid  from  thee,  when  I  was  made  in 
secret,  and  curiously  wrought  in  the  lowest  parts  of  the 
earth.  Thine  eyes  did  see  my  substance,  yet  being  im- 
perfect ;  and  in  thy  book  all  my  members  were  written, 
which  in  continuance  were  fashioned,  when  as  yet  there 
was  none  of  them.  How  precious  also  are  thy  thoughts 
unto  me,  O  God !  how  great  is  the  sum  of  them  !  If  I 
should  count  them,  they  are  more  in  number  than  the 
sand :  when  I  awake,  I  am  still  with  thee. . . .  Search  me, 
O  God,  and  know  my  heart ;  try  me,  and  know  my 
thoughts;  and  see  if  there  be  any  wicked  way  in  me. 
and  lead  me  in  the  way  everlasting." 


INDEX. 


Acineta,  the,  what,  16. 

Acrogens,  families  of  the,  109. 

Actinozoa,  the,  171,  177. 

Agassiz  on  evolution,  41. 

Agave,  or  aloe  family,  the,  129. 

Algae,  families  of  the,  91. 

Algae,  the  higher,  99. 

Amaryllidaceae,    (amaryilis    family,) 
the,  128. 

Amoeboid  movement,  why  so  called, 
29. 

Amphibia,  the,  242,  251. 

Amphibia,  why  so  called,  250. 

Analogous,  anatomical  import  of  the 
term,  76. 

Anatomy,  import  of  the  term,  9. 

Anaxagoras,  teachings  of,  IT. 

Animal  kingdom,  four  primary  di- 
visions of  the,  78. 
subdivisions  of  the,  82. 

Animals,  souls  of,  13. 

Arachnoidiscus  Ehrenbergii,  the,  93. 

Arrowroot  family,  the,  128. 

Articulata,  the,  213. 

Articulates,  construction  of  the,  78. 

Arum  family,  the,  131. 

Asteroidea,  the,  185. 

Atomic  theory,  the,  noticed,  18. 

Aves,  or  birds,  256. 

Banana  family,  the,  127. 

Beale,  Dr.,  quotation  from  on  life, 

17- 

Bichat's  definition  of  life,  12. 
Bimana,  import  of  the  term,  278. 
Biology,  import  of  the  term,  9. 
teachings  of,  10,  25. 
confirmatory  of  dualism,  n. 
Bioplasm,  what,  26,  33. 
how  nourished,  26. 
all  animal  life  originated  from, 

27. 

growth  an  essential  property  of, 
30. 


Birds,  families  of,  256. 
Blood,  circulation  of  the,   in  verte- 
brates, 241. 

in  amphibia  and  reptiles,  242. 
in  birds  and  mammals,  242. 
Botany,  definition  of  the  term,  9. 
Brachiopod,  the,  192,  196. 
Bromeliaceae    family,    (pine    apple,) 
128. 

Carnivora,  (beasts  of  prey,)  the,  275. 
Carpenter,  Dr.  W.  B.,  his  definition 

of  life,  12. 

Cephalopodae,  the,  192,  208. 
Characeae,  the,  109. 
Ccelenteratae,  the,  171. 
Coleridge,  on  life,  12. 
Comatulidse,  the,  185. 
Confervas,  the,  91. 
Coniferous  plants,  the,  142. 
Conjugateae,  (stoneworts,)  the,  91. 
Conscience,  288. 
Consciousness,  282. 
Construction  of  mollusks,  78. 

of  radiates,  78. 

of  vertebrates,  78. 
Crustacea,  the,  220. 
Cuvier,  his  divisions  of  the  animal 

kingdom,  78. 
Cyperaceae,  the,  125. 

Democritus,  teachings  of,  10. 
Desmidiaceae,  family  of  the,  88. 
Diatomaceae,  family  of  the,  92. 
Diatoma  vulgare,  the,  95. 
Dipnoi,  the,  250. 
Dualism,  10,  18,  37. 

Echinodermata,  (spiny-skinned,)  the, 

•171,  184. 

Edentata,  (toothless,)  the,  269. 
Ehrenberg,  Professor,  on  Vorticella. 

14. 
Electricity,  -powers  of,  54. 


294 


INDEX. 


Endogens,  (to  produce  within,)  the, 

122,  132. 

Equistaceae,  (horsetails,)  the,  113. 
Evolution,  import  of  the  term,  40. 
not  a  modern  science,  41. 
Agassiz  on,  41. 

Exogens,  (to  .produce  outward,)  the, 
137,  160: 

Family,  or  tribe,  a,  what,  74. 

Ferns,  114. 

Fishes,  245. 

Functional  character  of  organs,  77. 

Fungi,  103,  105,  106. 

Gasteropoda,  the,  192,  2OI. 
Generations,  alternation  of,  48. 

three  modes  of,  49. 
Genus,  what,  75. 
Ginger  family,  the,  128. 
Graminese,  (grass  family,)  124. 
Grammataphora,  the,  95. 
Gregarinidse,  the,  (parasitic  plants,) 

162. 

Growth  an  essential  property  of  bio- 
plasm, 30. 

Haeckel,  on  life,  12. 
Heliopelta,  (sun-shield,)  the,  95. 
Hepaticre,  (liverworts,)  the,  112. 
Homologous,  import  of  the  term,  76. 
Horsetails,  the,  109. 
Human  type,  the,  281. 
Hydra,  why  so  called,  172. 
Hydrozoa,  the,  171. 

Ideas,  relations  of,  287. 

Imagination,  the,  faculty  of,  288. 

Inanimate  things  incapable  of  pro- 
ducing animate,  19. 

Infusoria,  the,  14,  16,  23,  24,  164. 

Insecta,  the,  227. 

Invertebrates,  nervous  system  of, 
244. 

Iridacese,  (iris  family,)  the,  128. 

Isthmia  nervosa,  the,  95. 

Judgment,  the,  faculty  of,  288. 

Lamellibranchiata,  the,  192,  196. 
Leucippus,  teachings  of,  10. 
Lichens,  the,  101. 
Life,  various  definitions  of,  12. 
the  result  of  power,  21. 


Light,  influence  and  action  of,  54. 
Lily  family,  the,  130. 
Liverworts,  (hepaticee,)  the,  109,  112 
Long-wings,  the,  260. 

Man,  281. 

antiquity  of,  290. 

unity  of,  289. 

varieties  of,  290. 
Mammalia,  the.  267. 
Marantaceoe,  (arrowroot  family,)  the, 

128. 

Marsipobranchs,  the,  247. 
Marsupiala,     (pouch-bearers,)     the. 

269. 

Memory,  286. 
Molecular  movement,  what,  29. 

coalescence,  what,  56. 
Mollusca,  the,  192. 
Mollusks,  construction  of  the,  78. 
Monera,  the,  162. 
Monism,  the  theory  of,  10,  17. 
Morphology,  import  of  term,  9. 
Mosses,  u 6. 

Navicula,  the,  96. 

Nervous  system  of  vertebrates,  242. 

of  invertebrates,  244. 
Nostocs,  what,  91. 
Nutrition  essential  to  life,  31. 

Orchids,  the,  129. 
Order,  an,  what,  74. 
Organic  nature,  unity  of,  73. 
Oscillatoria,  what,  01. 
Osmotic  action,  what,  55. 

Palmellacece,  family  of  the,  87. 
Palmogloea  macrococca,  the,  84. 
Parentage,    sexual   and   non-sexual, 

43- 
Park,    Mungo,    striking    experience 

of,  120. 

Partheno-genesis,  what,  49. 
Perception,  faculty  of,  286. 
Pharyngobranchs,  order  of,  247. 
Physiology,  import  of  the  term,  9. 
Pigeon,  263. 

Pine-apple  family,  the,  128. 
Plato,  teachings  of,  u. 
Polyzoa,  (sea-moss,)  the,  192. 
Primitive  forms  of  life,  simple,  27. 
Protococcus  pluvialis,  the,  85. 
Protophytes,  life-history  of  the,  84 


INDEX. 


295 


Protoplasm,  physical  basis  of  life,  28. 
Protozoa,  or  primitive  animals,  161. 

Quadrumana,  (four-handed,)  the,  276. 

Radiates,  construction  of,  78. 

ho\v  distinguished,  170. 
Haveners,  the,  265. 
Reptiles,  the  circulation  of  the  blood 

in,  245. 

Reptilia,  the,  252. 
Resemblance,  parental,  43. 
Rhizopoda,  what,  162. 
Rodentia,  (gnawers,)  the,  270. 
Runners,  the,  262. 

Science    not    opposed    to    revealed 

truth,  n. 

Scratchers,  or  fowls,  the,  262. 
Screw-pine  family,  the,  131. 
Scriptures,  the,  teach  dualism,  u. 
Sedges,  the,  125. 
Sensation,  faculty  of,  286. 
Sentiments  and  Emotions,  the,  288. 
Short-wings,  the,  259. 
Species,  a,  what,  75. 
Spencer's  definition  of  life,  12. 


Sponges,  the,  167 

Spontaneous  motion  a  necessary  ac- 
companiment of  life,  29. 
Swimmers,  the,  259. 

Teleosls,  the,  248. 
Thallogens,  families  of  the,  98. 
Tissue,  what,  and  how  formed,-  52. 
Tunicata,  the,  192,  195. 
Type,  a,  what,  73,  75- 

Urodela,  the,  250. 

Vegetable    Kingdom,    divisions    of 

the,  8 1. 
Vertebrates,  construction  of  78,  239 

nervous  system  of  the,  242. 
Vertebrates,  five  classes  of,  245. 
Volition,  what,  288. 
Volvocinere,  family  of  the,  87. 
Vorticella,  the,  14,  16. 

Waders,  the,  260. 
Worms,  the,  214. 

Zingiberacene,  the,  128. 
Zoospores,  the,  88. 


THE   END. 


.    '  .-  • 


/—       f 


- 
.    i^M 

^ 


'•* 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN  INITIAL  FINE  OP  25  CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  5O  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


M(VR  26  1934 


4ILLL 


LD  21-100m-7,'33 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


